title: Video game addiction

text: Controversy around the diagnosis includes whether the disorder is a separate clinical entity or a manifestation of underlying psychiatric disorders. Research has approached the question from a variety of viewpoints, with no universally standardized or agreed definitions, leading to difficulties in developing evidence-based recommendations.


title: Video game addiction

text: In its report, the Council on Science and Public Health to the American Medical Association (AMA) used this two-hour-per-day limit to define "gaming overuse", citing the American Academy of Pediatrics guideline of no more than one to two hours per day of "screen time". However, the ESA document cited in the Council report does not contain the two-hour-per-day data.


title: Video game addiction

text: While the American Psychiatric Association (APA) does not recognise video game addiction as a disorder, in light of existing evidence, the organisation included video game addiction as a "condition requiring further study" in the DSM-5 as Internet gaming disorder. Video game addiction is a broader concept than internet gaming addiction, but most video game addiction is associated with internet gaming. APA suggests, like Khan, the effects (or symptoms) of video game addiction may be similar to those of other proposed psychological addictions. Video game addiction may be an impulse control disorder, similar to compulsive gambling The APA explains why Internet Gaming Disorder has been proposed as a disorder:This decision was based upon the large number of studies of this condition and the severity of its consequences. ... Because of the distinguishing features and increased risks of clinically significant problems associated with gaming in particular, the Workgroup recommended the inclusion of only internet gaming disorder in Section 3 of the DSM-5.


title: Video game addiction

text: Some players become more concerned with their interactions in the game than in their broader lives. Players may play many hours per day, neglect personal hygiene, gain or lose significant weight, disrupt sleep patterns resulting in sleep deprivation, play at work, avoid phone calls from friends, or lie about how much time they spend playing video games.


title: Video game addiction

text: One of the most commonly used instruments for the measurement of addiction, the PVP Questionnaire (Problem Video Game Playing Questionnaire, Tejeiro & Moran, 2002), was presented as a quantitative measure, not as a diagnostic tool. According to Griffiths, "all addictions (whether chemical or behavioral) are essentially about constant rewards and reinforcement". He proposes that addiction has six components: salience, mood modification, tolerance, withdrawal, conflict, and relapse. But the APA's nine criteria for diagnosing Internet Gaming Disorder were made by taking point of departure in eight different diagnostic/measuring tools proposed in other studies. Thus, the APA's criteria attempt to condense the scientific work on diagnosing Internet Gaming Disorder.


title: Video game addiction

text: The World Health Organization (WHO) had proposed and later included "gaming disorder" in the 11th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11), released in June 2018, which was approved by the World Health Assembly in May 2019. The use and enforcement of ICD-11 is expected to start on 1 January 2022.


title: Video game addiction

text: The first psychometric test to assess IGD was the Internet Gaming Disorder Test (IGD-20). This test includes 20 questions designed to assess the extent of problems caused by disordered gaming and the degree of symptoms experienced by gamers. The test was first published in a journal article published in the PLoS ONE journal on 14 October 2014.


title: Video game addiction

text: The Internet Gaming Disorder Scale–Short-Form (IGDS9-SF) is a short psychometric test to assess video game addiction according to the American Psychiatric Association framework for IGD. Recent review studies suggest that the IGDS9-SF presents with robust empirical and clinical evidence and is an effective tool to assess IGD. Moreover, the scale was adapted in several languages as Spanish, Chinese, Czech, German, and many more.


title: Video game addiction

text: On 3 June 2019, a screening tool for Gaming Disorder, specifically as defined by the World Health Organization, called the "Gaming Disorder Test" was published in a journal article.


title: Video game addiction

text: Younger people and men are more likely to experience a gaming disorder than older people and women respectively. Research shows that the average age of a gamer is 30 years old, and 32% of players are under 18.Adolescents are at a higher risk of sustaining video game disorder over time than adults. An international meta-analysis over 34 jurisdictions quantified the effect size of gender as small, with most effect in Asia, lesser in Europe and Africa, and null in North America, and further finding that economic factors, internet availability, social norms and addiction-related health factors mediate the effect of gender, with nations with a greater GDP per capita having less differences in video game addiction between genders.


title: Video game addiction

text: Comorbid psychiatric disorders act as both risk factors and consequences. Indeed, there is a strong association between video game addiction and anxiety, depression, ADHD, social phobia, and poor psycho-social support. ADHD and its symptoms, such as impulsivity and conduct problems, also increase risks of developing video game disorder. Although internet gaming disorder has a strong relationship with obsessive-compulsive disorder, it is not specific and internet gaming disorder is both phenomenologically and neurobiologically distinct, which indicates that internet gaming disorder is more characterized by impulsivity than compulsivity. Familial factors appear to play an important role, although not well understood.


title: Video game addiction

text: Some personality traits, such as high neuroticism, high impulsivity, and high aggressiveness are consistently significant predictors of internet gaming disorder, and combination of personality traits seem to play a pivotal role in the acquisition, maintenance and development of the disorder.


title: Video game addiction

text: Although there is much research since the 1980s on problematic online gaming use, the mechanisms are not well understood, due to inconsistent definitions used in studies.


title: Video game addiction

text: Some theories focus on the presumed built-in reward systems of video games, such as compulsion loops, to explain their potentially addictive nature. The anticipation of such rewards can create a neurological reaction that releases dopamine in the body, so that once the reward is obtained, the person will remember it as a pleasurable feeling. This has been found to be similar to the neurological reaction of other behavioral addictions such as substance abuse and gambling disorder.


title: Video game addiction

text: Mark Griffiths has proposed another reason online video games are potentially addictive is because they "can be played all day every day." The fact there is no end to the game can feel rewarding for some, and hence players are further engaged in the game.


title: Video game addiction

text: Long-term internet video/mobile game playing affects brain regions responsible for reward, impulse control and sensory-motor coordination. Structural analyses shown modifications in the volume of the ventral striatum, possibly as result of changes in rewards, and video game addicts had faulty inhibitory control and reward mechanisms. Video game playing is associated with dopamine release similar in magnitude to that of drug abuse and gambling, and the presentation of gaming pictures activates brain regions similarly to drug pictures for drug addicts. Treatment studies which used fMRI to monitor the brain connectivity changes found a decrease in the activity of the regions associated with cravings. Although there are evidences that video game addiction may be supported by similar neural mechanisms underlying drug abuse, as video game and internet addictions reduce the sensitivity of the dopaminergic reward system, it is still premature to conclude that this addiction is equivalent to substance addictions, as the research is in its early stages. There is evidence of a dual processing model of digital technology addictions characterized by an imbalance between the reactive and the reflective reward systems. Other studies shown increased difficulties in decision making in specific contexts, such as risky situations but not in ambiguous situations, and an increased preference for short-term rewards. Although the number of neuroimaging studies on internet gaming disorder is rising, there are several methodological shortcomings, particularly in the inconsistency of psychometric assessments. Furthermore, the conclusions on reduced inhibition should be moderated, as only one study included a functional control, which then showed no difference in inhibition.


title: Video game addiction

text: A meta-analytic review of the research concluded the evidence suggests video game addiction arises out of other mental health problems, rather than causing them. Thus it is unclear whether video game addiction should be considered a unique diagnosis.


title: Video game addiction

text: As concern over video game addiction grows, the use of psychopharmacology, psychotherapy, twelve-step programs, and use of continuing developing treatment enhancements have been proposed to treat this disorder. Empirical studies indeed indicate that internet gaming disorder is associated with detrimental health-related outcomes. However, the clinical trials of potential treatments remain of low quality, except for cognitive-behavioral therapies, which shows efficacy to reduce gaming disorder and depressive symptoms but not total time spent. Although there is a scientific consensus that cognitive-behavioral therapy is preferable to pharmacological treatment, it remains difficult to make definitive statements about its benefits and efficiency due to methodological inconsistencies and lack of follow-up. Since efficacious treatments have not been well established, prevention of video gaming disorder is crucial. Some evidence suggest that up to 50% of people affected by the internet gaming disorder may recover naturally.


title: Video game addiction

text: Some countries, such as South Korea, China, the Netherlands, Canada, and the United States, have responded to the perceived threat of video game addiction by opening treatment centres.


title: Video game addiction

text: China was the first country to treat "internet addiction" clinically in 2008. The Chinese government operates several clinics to treat those who overuse online games, chatting and web surfing. Treatment for the patients, most of whom have been forced to attend by parents or government officials, includes various forms of pain including shock therapy. In August 2009, Deng Sanshan was reportedly beaten to death in a correctional facility for video game and Web addiction. Most of the addiction "boot camps" in China are actually extralegal militaristically managed centers, but have remained popular despite growing controversy over their practices.


title: Video game addiction

text: In 2019, China set up a curfew, banning minors from playing between certain hours. In 2021, China government published a new policy to force corporations to only serve underage teenagers on Friday, Saturday, and Sunday between 8 pm to 9 pm.


title: Video game addiction

text: In June 2006, the Smith and Jones clinic in Amsterdam—which has now gone bankrupt—became the first treatment facility in Europe to offer a residential treatment program for compulsive gamers. Keith Bakker, founder and former head of the clinic, has stated that 90% of the young people who seek treatment for compulsive computer gaming are not addicted.


title: Video game addiction

text: At a Computer Addiction Services center in Richmond, British Columbia, excessive gaming accounts for 80% of one youth counselor's caseload.


title: Video game addiction

text: In 2018, the National Health Service announced its plans to open a treatment center, run by the Central and North West London NHS foundation trust, that will initially focus on gaming disorder, but is planned to expand to cover other internet-based addictions. The specialist treatment center opened in 2019 for treating adolescents and young people aged 13–25 who are addicted to video games.


title: Video game addiction

text: The most frequent physical health-related outcome are alterations in physical functioning such as somatization and sleep disturbances. Preliminary evidence suggest that internet gaming disorder and the induced sedentarity may contribute to a lack of physical exercise, even though the relationship is not causal.


title: Video game addiction

text: The prevalence of internet gaming disorder range from 0.7% to 25.5% worldwide, or 1.0% to 26.8% worldwide, and 3.5% to 17% in China, and is higher among males than females and among younger than older people, with geographical region being an insignificant contributor. The prevalence was found to be 5.06% among a high-school student population from Sri Lanka, suggesting an increasing trend in low- and middle-income countries as well. A longer time spent on video games predicts a tendency towards pathological gaming in the future. The studies, however, used various methodologies and definitions, which renders consensus difficult to achieve and may explain the wide range of prevalence.


title: Video game addiction

text: A meta-analytic review of pathological gaming studies concluded that about 3% of gamers may experience some symptoms of pathological gaming. The report noted problems in the field with defining and measuring pathological gaming and concluded that pathological gaming behaviors were more likely the product of underlying mental health problems rather than the inverse.


title: Video game addiction

text: Barnett and Coulson expressed concern that much of the debate on the issue of addiction may be a knee jerk response stimulated by poor understanding of games and game players. Such issues may lead both society and scholars to exaggerate the prevalence and nature of problematic gaming, and over-focus on games specifically, while ignoring underlying mental health issues. However, Problem gamblers have a higher chance for getting mental illness as well.


title: Video game addiction

text: Other scholars have cautioned that comparing the symptoms of problematic gaming with problematic gambling is flawed, and that such comparisons may introduce research artifacts and artificially inflate prevalence estimates. For instance, Richard Wood has observed that behaviors which are problematic in regards to gambling may not be as problematic when put into the context of other behaviors that are rewarding such as gaming. Similarly, Barnett and Coulson have cautioned that discussions of problematic gaming have moved forward prematurely without proper understanding of the symptoms, proper assessment and consequences.


title: Video game addiction

text: Rather than video gaming disorder being a subtype of gambling disorder, a majority of researchers support the idea of video game addiction being a part of a more comprehensive framework of impulse control disorders with "pathological technology use" with similar characteristics, including the pathological use of video games, internet, computers and other interactive medias. Although internet and video game addictions are generally considered different from gambling disorder and substance abuse, there is a growing body of evidence indicating they share common features, including behavioral and neural features. Indeed, it is suggested that while behavioral addiction may differ with drug addictions in magnitude, they share several characteristics, with Hellman et al. proposing that the concept of addiction should be de-medicalized.


title: Video game addiction

text: On the contrary, a literature review found that as the video game addiction develops, online gaming addicts spend increasing amounts of time not only playing but also preparing for and organizing their playing sessions, suggesting this addiction may be behavioral rather than a disorder of impulse control. There is recent evidence suggesting that internet gaming disorder can cause two distinct types of dysfunctions: cognitive and metacognitive.


title: Video game addiction

text: Griffiths has suggested that psycho-social dependence may revolve around the intermittent reinforcements in the game and the need to belong. Hagedorn & Young have suggested that social dependence may arise due to video games occurring online where players interact with others and the relationships "often become more important for gamers than real-life relationships".


title: Video game addiction

text: Common challenges involve the reliability of the methodology and validity of the results in some studies. Many rely on self-surveys from university students and also lack time frames making it difficult to study the impact, if any, of addiction on a long term scale. Other concerns also address the definition of addiction and how to measure it, questioning whether or not time is a proper unit to determine how addicted someone is to gaming. Daria Joanna Kuss and Mark D. Griffiths have argued the current scientific knowledge on internet gaming addiction is copious in scope and complexity. They state that instead, a simple framework should be provided to allow all current and future studies to be categorized, as internet gaming addiction lies on a continuum beginning with etiology and risk factors all the way through the development of "full-blown" addiction and ending with ramifications and potential treatment. In addition, they caution the deployment of the label "addiction" since it heavily denotes the use of substances or engagement in certain behaviors. Finally, the researcher promotes other researchers to assess the validity and reliability of existing measures instead of developing additional measurement instruments.


title: Video game addiction

text: Other challenges include the lack of context of the participant's life and the negative portrayal of gaming addicts. Some state that gamers sometimes use video games to either escape from an uncomfortable environment or alleviate their already existing mental issues—both possibly important aspects in determining the psychological impact of gaming. Negative portrayal also deals with the lack of consistency in measuring addictive gaming. This leads to discussions that sometimes exaggerate the issue and create a misconception in some that they, themselves, may be addicted when they are not.


title: Video game addiction

text: The evidence of video game addiction to create withdrawal symptoms is very limited and thus debated, due to different definitions and low quality trials.


title: Video game addiction

text: The concept of video game disorder is itself being debated, with the overlap of its symptoms with other mental disorders, the unclear consensus on a definition and thresholds, and the lack of evidence raising doubts on whether or not this qualifies as a mental disorder of its own. Despite the lack of a unified definition, there is an emerging consensus among studies that Internet gaming disorder is mainly defined by three features: 1) withdrawal, 2) loss of control, and 3) conflict. Although the DSM-5 definition of video game disorder has a good fit to current methodological definitions used in trials and studies, there are still debates on the clinical pertinence.


title: Video game addiction

text: Michael Brody, M.D., head of the TV and Media Committee of the American Academy of Child and Adolescent Psychiatry, stated in a 2007 press release that "... there is not enough research on whether or not video games are addictive." However, Brody also cautioned that for some children and adolescents, "... it displaces physical activity and time spent on studies, with friends, and even with family."


title: Video game addiction

text: A major issue concerns the lack of consistent measures and definitions and of acquisition of follow-up data. Furthermore, the study design quality has not greatly improved between the 2000s and 2017. For instance, most studies measured internet gaming behaviors in terms of frequency of use (total time spent), without considering the type of game (e.g., MMORPG), the social context (e.g., physically or virtually with friends), nor the motivations (e.g., competitive, achievement-oriented "grinding"). Although the amount of time spent was postulated by Johanssonn and Götestam in 2004 to lead to pathological behaviors, it is unclear whether the time spent is a cause or a consequence of pathological use. These criticisms, however, mostly pertain to Western research since there is more data of higher quality available in Asian regions, where the Internet gaming disorder is more prevalent.


title: Video game addiction

text: A survey conducted in 2019 of 214 scholars shown that 60.8% agreed that pathological video game use could be a mental health problems, whereas 30.4% were skeptical. However, only 49.7% agreed with the DSM-5 definition of Internet gaming disorder, and 56.5% to the definition of the World Health Organization. Most scholars were worried that WHO's and DSM-5's inclusion of Internet gaming disorder was "overpathologizing normal youth" and "precipitated moral panic over video games". This indicates a lack of consensus on the issue .


title: Video game addiction

text: Video game addiction has been studied since the 1980s, and has seen a significant increase in the number of empirical studies since then.


title: Video game addiction

text: The press has reported concerns over online gaming since at least 1994, when "Wired" mentioned a college student who was playing a MUD game for 12 hours a day instead of attending class.


title: Video game addiction

text: Press reports have noted that some Finnish Defence Forces' conscripts were not mature enough to meet the demands of military life and were required to interrupt or postpone military service for a year. One reported source of the lack of needed social skills is overuse of computer games or the internet. "Forbes" termed this overuse "Web fixations" and stated they were responsible for 13 such interruptions or deferrals over the five years from 2000 to 2005.


title: Video game addiction

text: In an April 2008 article, "The Daily Telegraph" reported that surveys of 391 players of "Asheron's Call" showed that three percent of respondents experienced agitation when they were unable to play, or missed sleep or meals to play. The article reports that University of Bolton lead researcher John Charlton said, "Our research supports the idea that people who are heavily involved in game playing may be nearer to autistic spectrum disorders than people who have no interest in gaming."


title: Video game addiction

text: On 6 March 2009, the Canadian Broadcasting Corporation's (CBC) national news magazine program "the fifth estate" aired an hour-long report on video game addiction and the Brandon Crisp story, titled "Top Gun", subtitled "When a video gaming obsession turns to addiction and tragedy."


title: Video game addiction

text: In August 2010, "Wired" reported that a man in Hawaii, Craig Smallwood, sued the gaming company NCSoft for negligence and for not specifying that their game, "Lineage II", was so addictive. He alleged he would not have begun playing if he was aware he would become addicted. Smallwood says he has played "Lineage" for 20,000 hours between 2004 and 2009.


title: Video game addiction

text: In 2013, a man from China observed his son's addiction to video games, and decided to take action. He hired online assassins to kill his son's virtual avatar every time he logged in. He hoped that being relentlessly killed would help his son lose interest in this destructive habit.


title: Video game addiction

text: In the draft versions leading to the final ICD-11 document, gaming disorder was included alongside gambling disorder under "Disorders Due to Addictive Behaviors". The addition defines as "a pattern of persistent or recurrent gaming behaviour ('digital gaming' or 'video-gaming')", defined by three criteria: the lack of control over playing video games, priority given to video games over other interests, and the inability to stop playing video games even after being affected by negative consequences. For gaming disorder to be diagnosed, the behavior pattern must be of sufficient severity to result in significant impairment in personal, family, social, educational, occupational or other important areas of functioning and would normally have been evident for at least 12 months. Research shows gaming disorders can be associated with anxiety, depression, loneliness, obesity, sleeping disorders, attention problems, and stress.


title: Video game addiction

text: Vladimir Poznyak, the coordinator for the WHO Department of Mental Health and Substance Abuse, defended the addition of gaming disorder, believing the backlash against the addition to be a moral panic as they chose a very narrow definition that encompasses only the most extreme cases of gaming disorder. He said evaluating a disorder for inclusion is nominally done without any external feedback "to avoid interference from commercial and other entities which may have vested interest in the outcome of the process". Dr. Poznyak asserted that several medical professionals consulting on the ICD-11 did believe gaming disorder to be real, and by including it in the ICD-11, there can now be earnest efforts to define its causes and symptoms betters and methods to deal with it, and now include the video game industry within the conversation to help reduce the effects of video games on public health.


title: Video game addiction

text: The addition of "gaming disorder" to the ICD-11 was criticized by gamers and the video game industry, while some researchers remained skeptical. Some of these researchers said the evidence remains weak and "there is a genuine risk of abuse of diagnoses." A group of 26 scholars wrote an open letter to the WHO, suggesting that the proposed diagnostic categories lacked scientific merit and were likely to do more harm than good. In counter-argument, a group of fifty academic researchers in behavioral science agreed that the evidence to support gaming disorder was weak, but it would be best that WHO identify gaming disorder in ICD-11 so that it could be considered a clinical and public health need.


title: Video game addiction

text: A report, prepared by mental health experts at Oxford University, Johns Hopkins University, Stockholm University and the University of Sydney, sponsored by The Association for UK Interactive Entertainment argues that while there may be potential addiction associated with video gaming, it is premature to consider it a disorder without further study, given the stigmatisation that surrounds video, and ask the WHO to use caution when finalising the ICD draft. This report was promoted by 22 video game industry trade organizations including the Entertainment Software Association of the United States and Interactive Software Federation of Europe


title: Video game addiction

text: As the final approval of the ICD-11 neared, several video game trade associations issued a statement requesting WHO to reconsider the addition of "gaming disorder", stating that, "The evidence for its inclusion remains highly contested and inconclusive". The Entertainment Software Association had meetings with the WHO during December 2018 to try to convince them to hold off including gaming disorder within ICD-11, with more planned meetings to follow.


title: Video game addiction

text: According to ABC News, parents have many concerns about their children playing video games, including concerns about age appropriateness, the amount of time spent playing games, physical health, and aggressive behaviour.


title: Video game addiction

text: The first video game to attract political controversy was the 1978 arcade game "Space Invaders". In 1981, a political bill called the Control of Space Invaders (and other Electronic Games) Bill was drafted by British Labour Party MP George Foulkes in an attempt to ban the game for its "addictive properties" and for causing "deviancy". The bill was debated and only narrowly defeated in parliament by 114 votes to 94 votes.


title: Video game addiction

text: In August 2005, the government of the People's Republic of China, where more than 20 million people play online games, introduced an online gaming restriction limiting playing time to three hours, after which the player would be expelled from whichever game they were playing. In 2006, it relaxed the rule so only citizens under the age of 18 would face the limitation. Reports indicate underage gamers found ways to circumvent the measure. In July 2007, the rule was relaxed yet again. Internet games operating in China must require users identify themselves by resident identity numbers. After three hours, players under 18 are prompted to stop and "do suitable physical exercise". If they continue, their in-game points are "slashed in half". After five hours, all their points are automatically erased.


title: Video game addiction

text: In 2008 in the United States (US), one of the five Federal Communications Commission (FCC) Commissioners, Deborah Taylor Tate, stated that online gaming addiction was "one of the top reasons for college drop-outs". However, she did not mention a source for the statement nor identify its position in relation to other top reasons.


title: Video game addiction

text: In 2011, the South Korean government implemented a law, known as the Shutdown law or the Cinderella Law, which prohibits children under the age of 16 from playing online video games between the hours of 12:00 a.m. to 6:00 a.m. Later on, the law was amended and now children under the age of 16 can play after midnight if they have permission from their parents. In 2021, the South Korean government moved to abolish this law.


title: Video game addiction

text: A systematic review identified in 2017 three types of currently attempted governmental policies: 1) limiting the availability of video games (shutdown, fatigue system, parental controls), 2) reduce the risks and harm (warning messages), 3) provide addiction help services to gamers. Most of these policies were either not as efficient as intended or not yet evaluated for efficiency, which lead some researchers to prompt for a global public health approach to prevent the onset and progression of this disorder. Some researchers suggest that the video game industry should itself place preventive measures against video game addiction.


title: Video game addiction

text: There have been at least a few deaths caused directly by exhaustion from playing games for excessive periods of time.


title: Video game addiction

text: In 2005, thirteen-year-old Zhang Xiaoyi committed suicide by jumping from the top of a 24-story tower block in his home province Tianjin. After previously having spent two straight days playing online role-playing games in an Internet cafe, Zhang had told his parents that he had "been poisoned by games and could no longer control himself". His parents sued Aomeisoft, the China-region publisher of the game "World of Warcraft". The head of a software association said to gaming website Play.tm that same year: "In the hypothetical world created by such games, [players] become confident and gain satisfaction, which they cannot get in the real world."


title: Video game addiction

text: In 2007, a 26-year-old man identified only as "Zhang" died of a heart attack due to lack of physical activity following a seven-day gaming binge, while a 30-year-old man died in a Guangzhou Internet cafe after playing online games for three straight days.


title: Video game addiction

text: In 2005, 28-year old industrial repairman Seungseob Lee (Hangul: 이승섭) visited an Internet cafe in the city of Daegu and played "StarCraft" almost continuously for fifty hours. He went into cardiac arrest and died at a local hospital. A friend reported: "... he was a game addict. We all knew about it. He couldn't stop himself." About six weeks before his death, he was fired from his job, and his girlfriend, also an avid gamer, broke up with him.


title: Video game addiction

text: In 2009, Kim Sa-rang, a 3-month-old Korean girl, starved to death after both her parents spent hours each day in an Internet cafe, rearing a virtual child in an online game, "Prius Online". The death is covered in the 2014 documentary "Love Child".


title: Video game addiction

text: In November 2001, 21-year-old Wisconsinite Shawn Woolley committed suicide; it has been inferred that his death was related to the popular computer game "EverQuest". Shawn's mother said the suicide was due to a rejection or betrayal in the game from a character Shawn called "iluvyou".


title: Video game addiction

text: Ohio teenager Daniel Petric shot his parents, killing his mother, after they took away his copy of "Halo 3" in October 2007. In a sentencing hearing after the teen was found guilty of aggravated murder, the judge said, "I firmly believe that Daniel Petric had no idea at the time he hatched this plot that if he killed his parents they would be dead forever", in reference to his disconnection from reality caused by playing violent video games. On 16 June 2009, Petric was sentenced to 23 years to life in prison.


title: 75th Tony Awards

text: The 75th Tony Awards were held on June 12, 2022, to recognize achievement in Broadway productions during the 2021–22 season. The ceremony was held at Radio City Music Hall in New York City, and was broadcast in two separate parts on CBS and Paramount+. Ariana DeBose served as host of the main ceremony, while Darren Criss and Julianne Hough hosted the hour-long preshow. This is the first ceremony in Tony Awards history that aired live in all U.S. time zones.


title: 75th Tony Awards

text: The most winning productions of the season were the new play "The Lehman Trilogy", which won five awards, including Best Play, and the revival of Stephen Sondheim’s musical "Company", which also won five awards, including Best Revival of a Musical. The Pulitzer Prize-winning musical "A Strange Loop" was the most-nominated show of the season, with 11 nominations, and won Best Musical, becoming the first Best Musical winner to win only two awards total since "42nd Street" (1981).


title: 75th Tony Awards

text: With her nomination for Best Featured Actress in a Musical in "A Strange Loop", L Morgan Lee became the first openly transgender person to be nominated for a Tony. Additionally, with her win as a lead producer of "A Strange Loop", Jennifer Hudson became the seventeenth person to become an EGOT winner.


title: 75th Tony Awards

text: Returning to its usual June scheduling, the ceremony's telecast was split between Paramount+ and CBS. Paramount+ streamed an hour-long pre-show, "The Tony Awards: Act One", at 7:00 p.m. ET, which was hosted by Darren Criss and Julianne Hough and featured "special performances" and the presentation of selected awards. It was followed by the main ceremony telecast on CBS and Paramount+, which was hosted by Ariana DeBose. For the first time, the ceremony was televised live on the U.S. West Coast.


title: 75th Tony Awards

text: The Tony Awards eligibility cut-off date for the 2021–22 season is May 4, 2022 for all Broadway productions which meet all other eligibility requirements. Nominations for the 2022 Tony Awards were announced by Adrienne Warren and Joshua Henry on May 9, 2022. They were initially going to be announced on May 3, but were extended a week to accommodate possible COVID-19 outbreaks. A revival of "West Side Story" that opened on February 20, 2020 was considered ineligible for the 74th Tony Awards because too few nominators and voters had seen it before Broadway shut down on March 12, 2020 due to the pandemic, and it did not resume when Broadway reopened in September 2021.


title: 75th Tony Awards

text: Robert E. Wankel was awarded the Isabelle Stevenson Award for “his generosity and service to the welfare of our Broadway community, over the past four decades and, especially in the face of a global crisis." The award for Excellence in Theatre Education will also be brought back this year. The recipients of the Tony Honors for Excellence in Theatre include the Asian American Performers Action Coalition, Broadway for All, music copyist Emily Grishman, Feinstein's/54 Below, and United Scenic Artists (Local USA 829, IATSE). On May 23, 2022, it was announced that Angela Lansbury would be receiving a Special Tony Award for Lifetime Achievement. The Regional Tony Award was given to the Court Theatre. James C. Nicola, retiring artistic director of the New York Theatre Workshop after 34 years, also received a Special Tony Award.


title: 75th Tony Awards

text: The ceremony received generally favorable reviews from critics. On the review aggregator Rotten Tomatoes, the program received six positive and two negative reviews, for an approval rating of 75%.


title: 75th Tony Awards

text: In "Variety", Gordon Cox praised the opening number of the CBS telecast and DeBose's performance as host therein, singling out the performance as "hip and queer and sexy, and it satisfied the old-school avids as much as it made Broadway look like a place the cool kids might want to check out, too". Jennifer Vanasco of NPR also praised DeBose, writing "Let Ariana DeBose host everything [...] She was funny and playful, strutting into the audience and sitting on Andrew Garfield's lap. She was poignant, coming to tears as she talked about her theater teacher mentor. She was honest, gently commenting on the racial disparities in the theater industry". Writing for the Associated Press, Jocelyn Noveck called the telecast "exuberant" and said that it showed "Broadway is back, with verve and creativity, and it is here to stay. It just needs even more people filling the seats".


title: 75th Tony Awards

text: Johnny Oleksinski of the "New York Post" panned the show, describing it as "low-energy, poorly put-on", writing that DeBose's "songs and banter were forced and unfunny", and heavily criticizing the ceremony's tribute to Stephen Sondheim, which he deemed "far too modest [...] a total afterthought".


title: 75th Tony Awards

text: The CBS telecast was watched by 3.86 million viewers in the United States, marking a 39% increase from the previous year's ceremony, the lowest-rated Tony Awards broadcast since viewership was measured. However, when compared to the 73rd Tony Awards in 2019, which were the last one before the 75th to run three hours and the last one before the COVID-19 pandemic, viewership declined 29% between 2019 and 2022.


title: Andriy Biletsky

text: Andriy Yevheniyovych Biletsky (, ; born 5 August 1979) is a Ukrainian far-right politician. He is the leader of political party National Corps. He was the first commander of the volunteer militia Azov Battalion, and a co-founder of the nationalist movement Social-National Assembly. From 2014 until 2019 Biletsky was a Member of Ukrainian Parliament.


title: Andriy Biletsky

text: Andriy Biletsky was born in 1979 in Kharkiv, Soviet Union. Biletsky's father Yevheniy Mykhailovych Biletsky hailed from an old Cossack family that founded the village of Krasnopavlivka (Lozova Raion), while Biletsky's mother Olena Anatoliyivna Biletsky ("née" Lukashevych) descended from a noble family from Zhytomyr region, to which belong the Decembrist Vasiliy Lukashevich (Vasyl Lukashevych) who founded the "Little-Russian Secret Society".


title: Andriy Biletsky

text: In his youth, Biletsky practiced several types of martial arts and boxing. Unlike many Ukrainians, he declined to join the Vladimir Lenin All-Union Pioneer Organization. Biletsky, along with senior schoolmates, raised the Ukrainian flag over his school. His major patriotic influence in his youth was his father's gift of a book prohibited in the Soviet Union, History of Ukraine for Children by Anton Lototsky. During the Kosovo War, Biletsky and a group of other Ukrainians attempted to join the Yugoslav Army as volunteers to fight against the Kosovo Liberation Army (KLA), but the war ended before they arrived at the front. In 2001, Biletsky graduated with honors from the History faculty of the University of Kharkiv. His thesis was about the Ukrainian Insurgent Army. The same year Biletsky participated in the Ukraine without Kuchma (UBK) protests, for which he was placed under administrative arrest. The Security Service of Ukraine pressured the university administration to expel Biletsky from the institution.


title: Andriy Biletsky

text: In 2002 Biletsky became a leader of the Kharkiv branch of the political organization Tryzub, and was a member of the Kharkiv section of the Social-National Party of Ukraine (SNPU), but opposed the idea of its transformation into Svoboda.


title: Andriy Biletsky

text: After the transformation of SNPU into Svoboda and liquidation of the original Patriot of Ukraine, in 2005 Biletsky initiated a revival of the Patriot of Ukraine, independent from any political factions. The new Patriot of Ukraine initially consisted of the Kharkiv branches of UNA-UNSO, Tryzub, and former SNPU. Since 2005, Biletsky also cooperated with the newly established Ukrainian Conservative Party.


title: Andriy Biletsky

text: During the Euromaidan events, members of the Biletsky's Patriot of Ukraine were among the founders of Right Sector on 28 November 2013. On 24 February 2014, the Ukrainian parliament adopted a decision on the freedom of political prisoners. The next day, Biletsky and other prisoners were completely acquitted of all charges and freed from custody.


title: Andriy Biletsky

text: On 12 March 2014, Biletsky became a party leader in special operations for the "Right Sector - East," which included such regions as Poltava, Kharkiv, Donetsk, and Luhansk oblasts. On 5 May 2014, in Berdyansk Biletsky became a founder of the Azov Battalion (as a territorial battalion of patrol service), and its first commander. The battalion was initially composed of members of the Patriot of Ukraine, SNA, football fans (notably Dynamo Kyiv supporters) and the AutoMaidan movement. The paramilitary unit became known as the "Little black men" as an opposition to the Russian special operations "Little green men". It would be transformed from a militia into a regular regiment of the National Guard of Ukraine on 20 November 2014.


title: Andriy Biletsky

text: On 13 June 2014, Biletsky led his detachment in the successful First Battle of Mariupol. According to British military reporter Askold Krushelnycky, "Biletsky was cool in the evaluation of actions and giving orders calmly and, in my opinion, logically". On 2 August 2014, Biletsky, holding a rank of Major of Militsiya, was awarded the Order For Courage (III degree) and promoted to lieutenant colonel of police on 15 August 2014.


title: Andriy Biletsky

text: On 10 September 2014, Biletsky was admitted to the military council of the People's Front, yet did not become a member of the party. On 27 September 2014, he ran as an independent candidate in the 217th electoral district (Kyiv) for the 2014 Ukrainian parliamentary election and won by receiving 31,445 votes (33.75%). In parliament, he joined the inter-factional group UKROP. In October 2014, Ihor Mykhailenko replaced Biletsky as commander of Azov Battalion.


title: Andriy Biletsky

text: In an interview to LB.ua (Left Bank) given on 10 December 2014, Biletsky announced that the Patriot of Ukraine suspended its activities as a political organization due to the war, and would be absorbed primarily into the Azov Battalion. In the same interview Biletsky said that the logo of the battalion is different from the German Wolfsangel and symbolizes Ukrainian national idea.


title: Andriy Biletsky

text: In October 2016 Biletsky officially left the Ukrainian National Guard because Ukrainian elected officials were barred from military service, but he vowed to continue his military career "without titles".


title: Andriy Biletsky

text: During his first three years of work in Verkhovna Rada Biletsky participated only in 2% of votes, He took part in only 229 votings, taking the fifth place in the rating of deputies with the fewest votings. He missed 328 sittings of the Ukrainian parliament. He missed all sittings of the Verkhovna Rada in 2016 and did not appear in parliament as of March 2017. According to a research of the Committee of Voters of Ukraine, published in August 2017, Biletsky did not write any laws that were adopted in the Verkhovna Rada. With 30 unsuccessful projects, he is in the first place among the deputies who submitted unsuccessful draft laws.


title: Andriy Biletsky

text: In the 2019 Ukrainian parliamentary election he was placed 2nd on the joined list of Svoboda with the far-right National Corps, the Governmental Initiative of Yarosh and Right Sector. His party did not win enough votes to clear the 5% election threshold and thus did not gain any parliamentary seats.


title: Andriy Biletsky

text: In 2010, Biletsky said that the Ukrainian nation's mission is to "lead the white races of the world in a final crusade...against Semite-led Untermenschen".</ref> Biletsky denied ever making such remarks and said that it was a fake quotation fabricated by Sergey Lavrov to defame him.


title: Andriy Biletsky

text: Until 2011 Biletsky was in favour of forming a confederation between Russia and Ukraine, with Kyiv as its capital, according to BBC News Ukrainian.


title: Andriy Biletsky

text: "The Independent" reported in 2022 that Biletsky is also known as "White Leader". In 2013 he wrote a brochure called "The Word of the White Leader". According to a 2021 paper by political scientists Umland and Fedorenko, he had been known as white leader before 2014, but has subsequently claimed that "if someone called me white leader face-to-face, [that person] would have been beaten".


title: Andriy Biletsky

text: , the BBC, "The Independent" and "The Moscow Times" have described Biletsky as a white supremacist. As of 2014 he had been accused of neo-Nazi views by sociologist Volodymyr Ishchenko.


title: Andriy Biletsky

text: In 2018, "The Guardian" reported that Biletsky "has toned down his rhetoric in recent years". Freedom House initiative "Reporting Radicalism" reported that he has not publicly made racist remarks since 2014, but he does "invoke anti-LGBT+ rhetoric frequently". Umland and Fedorenko wrote in 2021 that he still publicly objects to multiculturalism, but has stated "to be a Ukrainian nationalist today is to believe in values, not racial prejudice", and announced that his party does not use ethnicity to define who can, or cannot, be part of the nation Ukraine.


title: Andriy Biletsky

text: According to the electronic declaration, in 2015, Biletsky received ₴ 58,990 (US$2,087) as salary in the Verkhovna Rada. He had ₴ 250,000 (US$8,846) in cash. The declaration also indicated an apartment in Kyiv (see below), which was recorded as belonging to Biletsky's spouse Yuliya. In the declaration for 2016, Biletsky indicated 115,652 hryvnia (US$4,423) as deputy salary, and ₴ 250,000 in cash.


title: Andriy Biletsky

text: From 2003 to 2016, Andriy Biletsky was married to Yuliya Oleksandrivna Biletskaya (née Brusenko); their son was born in 2007. In April 2016, the couple divorced.


title: Pat Roach

text: Francis Patrick Roach (19 May 1937 – 17 July 2004) was an English professional wrestler, martial artist and actor. During an acting career between the 1970s and the 1990s, he appeared in multiple films, usually cast as a support player strongman villain. He appeared in the "Indiana Jones" film series, as the West Country bricklayer Brian "Bomber" Busbridge in the 1980s British television series "Auf Wiedersehen, Pet", and in the role of Petty Officer Edgar Evans in the television production "The Last Place on Earth".


title: Pat Roach

text: Roach was born and brought up in Birmingham, West Midlands, the son of Francis "Frank" Roach (born 1905). He was National Judo Champion in 1960, and Midland Area Black Belt Champion in 1962.


title: Pat Roach

text: He began his professional wrestling career under the name of "Judo" Pat Roach. After his acting career had begun, he continued to wrestle under the name of "Bomber" Pat Roach, having previously been billed as "Big" Pat Roach before receiving affectionate cheering from the audience. He was trained by Alf Kent, his first official wrestling match was against George Selko in 1960. Roach held both the British and European heavyweight championships at one time.


title: Pat Roach

text: Roach made his acting debut as the red-bearded bouncer in the Korova Milkbar in Stanley Kubrick's "A Clockwork Orange". He worked on another Kubrick film, "Barry Lyndon", where he played a hand-to-hand brawler named Toole who engages Ryan O'Neal in a fistfight. Roach went on to play a number of strong-man supporting character roles in films in the 1970s, 80s, and 90s, including the nonspeaking role of Hephaestus in "Clash of the Titans".


title: Pat Roach

text: Pat cameoed as a SPECTRE assassin in the 'unofficial' James Bond film "Never Say Never Again", and as bandit-warlord Lord Brytag in the sword-and-sorcery film "Red Sonja". He appeared as the skull-helmeted General Kael in the film "Willow"; the evil wizard Thoth-Amon in "Conan the Destroyer" and as the Celtic chieftain in "".


title: Pat Roach

text: In 1985 he played Petty Officer Edgar Evans in the Central TV serial "The Last Place on Earth" about Captain Scott's expedition to the South Pole. Roach was turned down as Darth Vader in "Star Wars"; however, its director, George Lucas, subsequently cast him as several burly villains in the "Indiana Jones" film series in the 1980s. In "Raiders of the Lost Ark", he played two roles: the first being a giant Sherpa who fights Jones in the bar in Nepal, the second being a German Luftwaffe mechanic who fistfights with Jones before being killed by an aircraft's propeller blades on the airstrip in Egypt. In the next film, "Indiana Jones and the Temple of Doom", Roach played a Thuggee guard in a mine who fights with Jones before being killed in a rock crusher. His final appearance in the series was as a Gestapo officer in "Indiana Jones and the Last Crusade", he appears only briefly as the character's fight with Jones was cut because director Steven Spielberg considered the scene "too long" and served as a subplot.


title: Pat Roach

text: On television Roach played the down-to-earth and easy going Brian "Bomber" Busbridge in the long running comedy-drama "Auf Wiedersehen, Pet". He appeared in all four series, but was absent from the final two-part Christmas special.


title: Pat Roach

text: In the 1990s, Roach owned and co-managed a scrapyard in Saltley, Birmingham. He also ran a gym on Gravelly Hill North, Erdington, in North-East Birmingham.


title: Pat Roach

text: Roach died on 17 July 2004 of esophageal cancer. His body was buried in Bromsgrove Cemetery, Worcestershire.


title: Manchego

text: Manchego (officially , ) is a cheese made in the La Mancha region of Spain from the milk of sheep of the Manchega breed. It is aged between 60 days and 2 years.


title: Manchego

text: Manchego has a firm and compact consistency and a buttery texture, often containing small, unevenly distributed air pockets. The colour of the cheese varies from white to ivory-yellow, and the inedible rind from yellow to brownish-beige. The cheese has a distinctive flavour, well developed but not too strong, creamy with a slight piquancy, and leaves an aftertaste that is characteristic of sheep's milk.


title: Manchego

text: The designation is protected under Spain's denominación de origen regulatory classification system, and the cheese has been granted Protected Designation of Origin (PDO) status by the European Union.


title: Manchego

text: Manchego cheese can be made from pasteurised or raw milk; if the latter, it may be labelled (artisan). The only permitted additives are natural rennet or another approved coagulating enzyme and salt.


title: Manchego

text: The moulds in which the cheese is pressed are barrel-shaped. Traditionally, manchego cheese was made by pressing the curd in plaited esparto grass baskets, which left a distinctive zig-zag pattern (known as ) on the rind. Today, the same effect is achieved by the mould, the inside of which has a design in relief that imparts to the finished cheese an embossed pattern similar to that of woven esparto grass. The top and bottom surfaces of the cheese are impressed with a design of a head of wheat.


title: Manchego

text: During the maturation process, manchego cheese develops a natural rind. The regulations permit this to be washed, coated in paraffin, dipped in olive oil, or treated with certain approved transparent substances, but require that it must not be removed if the cheese is to be marketed as PDO.


title: Manchego

text: Cheeses that meet the PDO requirements carry a casein tab that is applied when the cheese is in the mould and bear a distinctive label that is issued by the Manchego Cheese Denomination of Origin Regulating Council; this carries the legend , a serial number, and artwork depicting Don Quixote de La Mancha.


title: Manchego

text: A cheese that is similar to manchego and made in the same region, but from a blend of cow's, goat's, and ewe's milk, is sold as , or cheese.


title: Manchego

text: Almost 60% of Spanish cheese with Denomination of Origin is Manchego, which makes it the main reference of Spanish cheese. As most of its production is exported, it is one of the most important ambassadors of Spain’s national gastronomy. La Mancha exported 5.9 million kg of this cheese in 2017, according to the Foundation for Manchego Cheese (Fundación C.R.D.O Queso Manchego).


title: Manchego

text: In Mexico and Spanish-speaking areas of the United States, or (manchego-type cheese) is the name given to an industrialized cow's milk cheese similar in taste to Monterey Jack. It melts well and is used as both a table cheese and for cooking. Apart from the name, this cheese has little in common with the Spanish variety.


title: Manchego

text: In Costa Rica, three companies (Dos Pinos, Los Alpes, and Monteverde) produce a manchego-type cheese (), which can come with a drawing of Don Quijote on the labels. One company also makes a manchego-type cheese with basil added. These Costa Rican cheeses can come dipped in paraffin wax, and some have the pattern pressed on the side.


title: Icelanders

text: Icelanders () are a North Germanic ethnic group and nation who are native to the island country of Iceland and speak Icelandic.


title: Icelanders

text: Icelanders established the country of Iceland in mid 930 AD when the Althing (Parliament) met for the first time. Iceland came under the reign of Norwegian, Swedish and Danish kings but regained full sovereignty and independence from the Danish monarchy on 1 December 1918, when the Kingdom of Iceland was established. On 17 June 1944, the monarchy was abolished and the Icelandic republic was founded. The language spoken is Icelandic, a North Germanic language, and Lutheranism is the predominant religion. Historical and DNA records indicate that around 60 to 80 percent of the male settlers were of Norse origin (primarily from Western Norway) and a similar percentage of the women were of Gaelic stock from Ireland and peripheral Scotland.


title: Icelanders

text: Iceland is a geologically young land mass, having formed an estimated 20 million years ago due to volcanic eruptions on the Mid-Atlantic ridge. One of the last larger islands to remain uninhabited, the first human settlement date is generally accepted to be 874 AD, although there is some evidence to suggest human activity prior to the Norse arrival.


title: Icelanders

text: The first Viking to sight Iceland was Gardar Svavarsson, who went off course due to harsh conditions when sailing from Norway to the Faroe Islands. His reports led to the first efforts to settle the island. Flóki Vilgerðarson (b. 9th century) was the first Norseman to sail to Iceland intentionally. His story is documented in the Landnámabók manuscript, and he is said to have named the island Ísland (Iceland). The first permanent settler in Iceland is usually considered to have been a Norwegian chieftain named Ingólfur Arnarson. He settled with his family in around 874, at a place he named "Bay of Smokes", or Reykjavík in Icelandic.


title: Icelanders

text: Following Ingólfur, and also in 874, another group of Norwegians set sail across the North Atlantic Ocean with their families, livestock, slaves, and possessions, escaping the domination of the first King of Norway, Harald Fairhair. They traveled 1,000 km (600 mi) in their Viking longships to the island of Iceland. These people were primarily of Norwegian, Irish or Gaelic Scottish origin. The Irish and the Scottish Gaels were either slaves or servants of the Norse chiefs, according to the Icelandic sagas, or descendants of a "group of Norsemen who had settled in Scotland and Ireland and intermarried with Gaelic-speaking people". Genetic evidence suggests that approximately 62% of the Icelandic maternal gene pool is derived from Ireland and Scotland, which is much higher than other Scandinavian countries, although comparable to the Faroese, while 37% is of Nordic origin. About 20–25% of the Icelandic paternal gene pool is of Gaelic origin, with the rest being Nordic.


title: Icelanders

text: The Icelandic Age of Settlement () is considered to have lasted from 874 to 930, at which point most of the island had been claimed and the (), the assembly of the Icelandic Commonwealth, was founded at Þingvellir.


title: Icelanders

text: In 930, on the Þingvellir () plain near Reykjavík, the chieftains and their families met and established the Alþingi, Iceland's first national assembly. However, the Alþingi lacked the power to enforce the laws it made. In 1262, struggles between rival chieftains left Iceland so divided that King Haakon IV of Norway was asked to step in as a final arbitrator for all disputes, as part of the Old Covenant. This is known as the Age of the Sturlungs.


title: Icelanders

text: Iceland was under Norwegian leadership until 1380, when the Royal House of Norway died out. At this point, both Iceland and Norway came under the control of the Danish Crown. With the introduction of absolute monarchy in Denmark, the Icelanders relinquished their autonomy to the crown, including the right to initiate and consent to legislation. This meant a loss of independence for Iceland, which led to nearly 300 years of decline: perhaps largely because Denmark and its Crown did not consider Iceland to be a colony to be supported and assisted. In particular, the lack of help in defense led to constant raids by marauding pirates along the Icelandic coasts.


title: Icelanders

text: Unlike Norway, Denmark did not need Iceland's fish and homespun wool. This created a dramatic deficit in Iceland's trade, and no new ships were built as a result. In 1602, Iceland was forbidden to trade with other countries by order of the Danish Government, and in the 18th century climatic conditions had reached an all-time low since Settlement.


title: Icelanders

text: In 1783–84, Laki, a volcanic fissure in the south of the island, erupted. The eruption produced about 15 km (3.6 mi) of basalt lava, and the total volume of tephra emitted was 0.91 km. The aerosols that built up caused a cooling effect in the Northern Hemisphere. The consequences for Iceland were catastrophic, with approximately 25–33% of the population dying in the famine of 1783 and 1784. Around 80% of sheep, 50% of cattle, and 50% of horses died of fluorosis from the 8 million tons of fluorine that were released. This disaster is known as the Mist Hardship (Icelandic: "Móðuharðindin").


title: Icelanders

text: In 1798–99, the Alþingi was discontinued for several decades, eventually being restored in 1844. It was moved to Reykjavík, the capital, after being held at Þingvellir for over nine centuries.


title: Icelanders

text: The 19th century brought significant improvement in the Icelanders' situation. A protest movement was led by Jón Sigurðsson, a statesman, historian, and authority on Icelandic literature. Inspired by the romantic and nationalist currents from mainland Europe, Jón protested strongly, through political journals and self-publications, for 'a return to national consciousness' and for political and social changes to be made to help speed up Iceland's development.


title: Icelanders

text: In 1854, the Danish government relaxed the trade ban that had been imposed in 1602, and Iceland gradually began to rejoin Western Europe economically and socially. With this return of contact with other peoples came a reawakening of Iceland's arts, especially its literature. Twenty years later in 1874, Iceland was granted a constitution. Icelanders today recognize Jón's efforts as largely responsible for their economic and social resurgence.


title: Icelanders

text: Iceland gained full sovereignty and independence from Denmark in 1918 after World War I. It became the Kingdom of Iceland. The King of Denmark also served as the King of Iceland but Iceland retained only formal ties with the Danish Crown. On 17 June 1944 the monarchy was abolished and a republic was established on Jón Sigurðsson's 133rd birthday. This ended nearly six centuries of ties with Denmark.


title: Icelanders

text: Due to their small founding population and history of relative isolation, Icelanders have often been considered highly genetically homogeneous as compared to other European populations. For this reason, along with the extensive genealogical records for much of the population that reach back to the settlement of Iceland, Icelanders have been the focus of considerable genomics research by both biotechnology companies and academic and medical researchers. It was, for example, possible for researchers to reconstruct much of the maternal genome of Iceland's first known black inhabitant, Hans Jonatan, from the DNA of his present-day descendants partly because the distinctively African parts of his genome were unique in Iceland until very recent times.


title: Icelanders

text: Genetic evidence shows that most DNA lineages found among Icelanders today can be traced to the settlement of Iceland, indicating that there has been relatively little immigration since. This evidence shows that the founder population of Iceland came from Ireland, Scotland, and Scandinavia: studies of mitochondrial DNA and Y-chromosomes indicate that 62% of Icelanders' matrilineal ancestry derives from Scotland and Ireland (with most of the rest being from Scandinavia), while 75% of their patrilineal ancestry derives from Scandinavia (with most of the rest being from the Irish and British Isles).


title: Icelanders

text: Other studies have identified other ancestries, however. One study of mitochondrial DNA, blood groups, and isozymes revealed a more variable population than expected, comparable to the diversity of some other Europeans. Another study showed that a tiny proportion of samples of contemporary Icelanders carry a more distant lineage, which belongs to the haplogroup C1e, which can possibly be traced to the settlement of the Americas around 14,000 years ago. This hints a small proportion of Icelanders have some Native American ancestry arising from Norse colonization of Greenland and North America.


title: Icelanders

text: Despite Iceland's historical isolation, the genetic makeup of Icelanders today is still quite different from the founding population, due to founder effects and genetic drift. One study found that the mean Norse ancestry among Iceland's settlers was 56%, whereas in the current population the figure was 70%. This indicates that Icelanders with increased levels of Norse ancestry had higher reproductive success.


title: Icelanders

text: The first Europeans to emigrate to and settle in Greenland were Icelanders who did so under the leadership of Erik the Red in the late 10th century CE and numbered around 500 people. Isolated fjords in this harsh land offered sufficient grazing to support cattle and sheep, though the climate was too cold for cereal crops. Royal trade ships from Norway occasionally went to Greenland to trade for walrus tusks and falcons. The population eventually reached a high point of perhaps 3,000 in two communities and developed independent institutions before fading away during the 15th century. A papal legation was sent there as late as 1492, the year Columbus attempted to find a shorter spice route to Asia but instead encountered the Americas.


title: Icelanders

text: According to the "Saga of Eric the Red", Icelandic immigration to North America dates back to Vinland circa 1006. The colony was believed to be short-lived and abandoned by the 1020s. European settlement of the region was not archeologically and historically confirmed as more than legend until the 1960s. The former Norse site, now known as L'Anse aux Meadows, pre-dated the arrival of Columbus in the Americas by almost 500 years.


title: Icelanders

text: A more recent instance of Icelandic emigration to North America occurred in 1855, when a small group settled in Spanish Fork, Utah. Another Icelandic colony formed in Washington Island, Wisconsin. Immigration to the United States and Canada began in earnest in the 1870s, with most migrants initially settling in the Great Lakes area. These settlers were fleeing famine and overcrowding on Iceland. Today, there are sizable communities of Icelandic descent in both the United States and Canada. Gimli, in Manitoba, Canada, is home to the largest population of Icelanders outside of the main island of Iceland.


title: Icelanders

text: From the mid-1990s, Iceland experienced rising immigration. By 2017 the population of first-generation immigrants (defined as people born abroad with both parents foreign-born and all grandparents foreign-born) stood at 35,997 (10.6% of residents), and the population of second-generation immigrants at 4,473. Correspondingly, the numbers of foreign-born people acquiring Icelandic citizenship are markedly higher than in the 1990s, standing at 703 in 2016. Correspondingly, Icelandic identity is gradually shifting towards a more multicultural form.


title: Icelanders

text: Icelandic, a North Germanic language, is the official language of Iceland ("de facto"; the laws are silent about the issue). Icelandic has inflectional grammar comparable to Latin, Ancient Greek, more closely to Old English and practically identical to Old Norse.


title: Icelanders

text: Old Icelandic literature can be divided into several categories. Three are best known to foreigners: Eddic poetry, skaldic poetry, and saga literature, if saga literature is understood broadly. Eddic poetry is made up of heroic and mythological poems. Poetry that praises someone is considered skaldic poetry or court poetry. Finally, saga literature is prose, ranging from pure fiction to fairly factual history.


title: Icelanders

text: Written Icelandic has changed little since the 13th century. Because of this modern readers can understand the Icelanders' sagas. The sagas tell of events in Iceland in the 10th and early 11th centuries. They are considered to be the best-known pieces of Icelandic literature.


title: Icelanders

text: The elder or "Poetic Edda", the younger or "Prose Edda", and the sagas are the major pieces of Icelandic literature. The "Poetic Edda" is a collection of poems and stories from the late 10th century, whereas the younger or "Prose Edda" is a manual of poetry that contains many stories of Norse mythology.


title: Icelanders

text: Iceland embraced Christianity in c. AD 1000, in what is called the "kristnitaka", and the country, while mostly secular in observance, is still predominantly Christian culturally. The Lutheran church claims some 84% of the total population. While early Icelandic Christianity was more lax in its observances than traditional Catholicism, Pietism, a religious movement imported from Denmark in the 18th century, had a marked effect on the island. By discouraging all but religious leisure activities, it fostered a certain dourness, which was for a long time considered an Icelandic stereotype. At the same time, it also led to a boom in printing, and Iceland today is one of the most literate societies in the world.


title: Icelanders

text: While Catholicism was supplanted by Protestantism during the Reformation, most other world religions are now represented on the island: there are small Protestant Free Churches and Catholic communities, and even a nascent Muslim community, composed of both immigrants and local converts. Perhaps unique to Iceland is the fast-growing "Ásatrúarfélag", a legally recognized revival of the pre-Christian Nordic religion of the original settlers. According to the Roman Catholic Diocese of Reykjavík, there were only approximately 30 Jews in Iceland as of 2001. The former First Lady of Iceland Dorrit Moussaieff was an Israeli-born Bukharian Jew.


title: Icelanders

text: Icelandic cuisine consists mainly of fish, lamb, and dairy. Fish was once the main part of an Icelander's diet but has recently given way to meats such as beef, pork, and poultry.


title: Icelanders

text: Iceland has many traditional foods called Þorramatur. These foods include smoked and salted lamb, singed sheep heads, dried fish, smoked and pickled salmon, and cured shark. Andrew Zimmern, a chef who has traveled the world on his show "Bizarre Foods with Andrew Zimmern", responded to the question "What's the most disgusting thing you've ever eaten?" with the response "That would have to be the fermented shark fin I had in Iceland." Fermented shark fin is a form of Þorramatur.


title: Icelanders

text: The earliest indigenous Icelandic music was the "rímur", epic tales from the Viking era that were often performed a cappella. Christianity played a major role in the development of Icelandic music, with many hymns being written in the local idiom. Hallgrímur Pétursson, a poet and priest, is noted for writing many of these hymns in the 17th century. The island's relative isolation ensured that the music maintained its regional flavor. It was only in the 19th century that the first pipe organs, prevalent in European religious music, first appeared on the island.


title: Icelanders

text: Many singers, groups, and forms of music have come from Iceland. Most Icelandic music contains vibrant folk and pop traditions. Some more recent groups and singers are Voces Thules, The Sugarcubes, Björk, Sigur Rós, and Of Monsters and Men.


title: Icelanders

text: The national anthem is "Ó Guð vors lands" (), written by Matthías Jochumsson, with music by Sveinbjörn Sveinbjörnsson. The song was written in 1874, when Iceland celebrated its one thousandth anniversary of settlement on the island. It was originally published with the title "A Hymn in Commemoration of Iceland's Thousand Years".


title: Icelanders

text: Iceland's men's national football team participated in their first FIFA World Cup in 2018, after reaching the quarter finals of its first major international tournament, UEFA Euro 2016. The women's national football team has yet to reach a World Cup; its best result at a major international event was a quarterfinal finish in UEFA Women's Euro 2013. The country's first Olympic participation was in the 1912 Summer Olympics; however, they did not participate again until the 1936 Summer Olympics. Their first appearance at the Winter Games was at the 1948 Winter Olympics. In 1956, Vilhjálmur Einarsson won the Olympic silver medal for the triple jump. The Icelandic national handball team has enjoyed relative success. The team received a silver medal at the 2008 Olympic Games and a 3rd place at the 2010 European Men's Handball Championship.


title: Michigan Panthers (2022)

text: The Michigan Panthers are a professional American football team. The Panthers compete in the United States Football League (USFL) as a member of the North Division. The team plays their home games at Protective Stadium and Legion Field in Birmingham, Alabama, which also hosts the University of Alabama at Birmingham Blazers.


title: Michigan Panthers (2022)

text: The Michigan Panthers were one of eight teams that were officially announced as a USFL franchise on "The Herd with Colin Cowherd" on November 22, 2021.


title: Michigan Panthers (2022)

text: On January 27, 2022, it was announced on "The Herd with Colin Cowherd" that former NFL Head coach Jeff Fisher was named the head coach and general manager of the Panthers.


title: Michigan Panthers (2022)

text: Initially, each team carried a 38-man active roster and a 7-man practice squad, but the rosters were increased to 40 active players and 50 total in May, 2022.


title: Circumstellar habitable zone

text: In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence.


title: Circumstellar habitable zone

text: The habitable zone is also called the Goldilocks zone, a metaphor, allusion and antonomasia of the children's fairy tale of "Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right".


title: Circumstellar habitable zone

text: Since the concept was first presented in 1953, many stars have been confirmed to possess a CHZ planet, including some systems that consist of multiple CHZ planets. Most such planets, being either super-Earths or gas giants, are more massive than Earth, because massive planets are easier to detect. On November 4, 2013, astronomers reported, based on "Kepler" data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way. About 11 billion of these may be orbiting Sun-like stars. Proxima Centauri b, located about 4.2 light-years (1.3 parsecs) from Earth in the constellation of Centaurus, is the nearest known exoplanet, and is orbiting in the habitable zone of its star. The CHZ is also of particular interest to the emerging field of habitability of natural satellites, because planetary-mass moons in the CHZ might outnumber planets.


title: Circumstellar habitable zone

text: In subsequent decades, the CHZ concept began to be challenged as a primary criterion for life, so the concept is still evolving. Since the discovery of evidence for extraterrestrial liquid water, substantial quantities of it are now thought to occur outside the circumstellar habitable zone. The concept of deep biospheres, like Earth's, that exist independently of stellar energy, are now generally accepted in astrobiology given the large amount of liquid water known to exist within in lithospheres and asthenospheres of the Solar System. Sustained by other energy sources, such as tidal heating or radioactive decay or pressurized by non-atmospheric means, liquid water may be found even on rogue planets, or their moons. Liquid water can also exist at a wider range of temperatures and pressures as a solution, for example with sodium chlorides in seawater on Earth, chlorides and sulphates on equatorial Mars, or ammoniates, due to its different colligative properties. In addition, other circumstellar zones, where non-water solvents favorable to hypothetical life based on alternative biochemistries could exist in liquid form at the surface, have been proposed.


title: Circumstellar habitable zone

text: An estimate of the range of distances from the Sun allowing the existence of liquid water appears in Newton's "Principia" (Book III, Section 1, corol. 4).


title: Circumstellar habitable zone

text: in 1913, by Edward Maunder in his book "Are The Planets Inhabited?". The concept was later discussed in 1953 by Hubertus Strughold, who in his treatise "The Green and the Red Planet: A Physiological Study of the Possibility of Life on Mars", coined the term "ecosphere" and referred to various "zones" in which life could emerge. In the same year, Harlow Shapley wrote "Liquid Water Belt", which described the same concept in further scientific detail. Both works stressed the importance of liquid water to life. Su-Shu Huang, an American astrophysicist, first introduced the term "habitable zone" in 1959 to refer to the area around a star where liquid water could exist on a sufficiently large body, and was the first to introduce it in the context of planetary habitability and extraterrestrial life. A major early contributor to habitable zone concept, Huang argued in 1960 that circumstellar habitable zones, and by extension extraterrestrial life, would be uncommon in multiple star systems, given the gravitational instabilities of those systems.


title: Circumstellar habitable zone

text: The concept of habitable zones was further developed in 1964 by Stephen H. Dole in his book "Habitable Planets for Man", in which he discussed the concept of circumstellar habitable zone as well as various other determinants of planetary habitability, eventually estimating the number of habitable planets in the Milky Way to be about 600 million. At the same time, science-fiction author Isaac Asimov introduced the concept of a circumstellar habitable zone to the general public through his various explorations of space colonization. The term "Goldilocks zone" emerged in the 1970s, referencing specifically a region around a star whose temperature is "just right" for water to be present in the liquid phase. In 1993, astronomer James Kasting introduced the term "circumstellar habitable zone" to refer more precisely to the region then (and still) known as the habitable zone. Kasting was the first to present a detailed model for the habitable zone for exoplanets.


title: Circumstellar habitable zone

text: An update to habitable zone concept came in 2000, when astronomers Peter Ward and Donald Brownlee introduced the idea of the "galactic habitable zone", which they later developed with Guillermo Gonzalez. The galactic habitable zone, defined as the region where life is most likely to emerge in a galaxy, encompasses those regions close enough to a galactic center that stars there are enriched with heavier elements, but not so close that star systems, planetary orbits, and the emergence of life would be frequently disrupted by the intense radiation and enormous gravitational forces commonly found at galactic centers.


title: Circumstellar habitable zone

text: Subsequently, some astrobiologists propose that the concept be extended to other solvents, including dihydrogen, sulfuric acid, dinitrogen, formamide, and methane, among others, which would support hypothetical life forms that use an alternative biochemistry. In 2013, further developments in habitable zone concepts were made with the proposal of a circum "planetary" habitable zone, also known as the "habitable edge", to encompass the region around a planet where the orbits of natural satellites would not be disrupted, and at the same time tidal heating from the planet would not cause liquid water to boil away.


title: Circumstellar habitable zone

text: It has been noted that the current term of 'circumstellar habitable zone' poses confusion as the name suggests that planets within this region will possess a habitable environment. However, surface conditions are dependent on a host of different individual properties of that planet. This misunderstanding is reflected in excited reports of 'habitable planets'. Since it is completely unknown whether conditions on these distant CHZ worlds could host life, different terminology is needed.


title: Circumstellar habitable zone

text: Whether a body is in the circumstellar habitable zone of its host star is dependent on the radius of the planet's orbit (for natural satellites, the host planet's orbit), the mass of the body itself, and the radiative flux of the host star. Given the large spread in the masses of planets within a circumstellar habitable zone, coupled with the discovery of super-Earth planets which can sustain thicker atmospheres and stronger magnetic fields than Earth, circumstellar habitable zones are now split into two separate regions—a "conservative habitable zone" in which lower-mass planets like Earth can remain habitable, complemented by a larger "extended habitable zone" in which a planet like Venus, with stronger greenhouse effects, can have the right temperature for liquid water to exist at the surface.


title: Circumstellar habitable zone

text: Estimates for the habitable zone within the Solar System range from 0.38 to 10.0 astronomical units, though arriving at these estimates has been challenging for a variety of reasons. Numerous planetary mass objects orbit within, or close to, this range and as such receive sufficient sunlight to raise temperatures above the freezing point of water. However, their atmospheric conditions vary substantially.


title: Circumstellar habitable zone

text: The aphelion of Venus, for example, touches the inner edge of the zone in most estimates and while atmospheric pressure at the surface is sufficient for liquid water, a strong greenhouse effect raises surface temperatures to at which water can only exist as vapour. The entire orbits of the Moon, Mars, and numerous asteroids also lie within various estimates of the habitable zone. Only at Mars' lowest elevations (less than 30% of the planet's surface) is atmospheric pressure and temperature sufficient for water to, if present, exist in liquid form for short periods. At Hellas Basin, for example, atmospheric pressures can reach 1,115 Pa and temperatures above zero Celsius (about the triple point for water) for 70 days in the Martian year. Despite indirect evidence in the form of seasonal flows on warm Martian slopes, no confirmation has been made of the presence of liquid water there. While other objects orbit partly within this zone, including comets, Ceres is the only one of planetary mass. A combination of low mass and an inability to mitigate evaporation and atmosphere loss against the solar wind make it impossible for these bodies to sustain liquid water on their surface.


title: Circumstellar habitable zone

text: Despite this, studies are strongly suggestive of past liquid water on the surface of Venus, Mars, Vesta and Ceres, suggesting a more common phenomenon than previously thought. Since sustainable liquid water is thought to be essential to support complex life, most estimates, therefore, are inferred from the effect that a repositioned orbit would have on the habitability of Earth or Venus as their surface gravity allows sufficient atmosphere to be retained for several billion years.


title: Circumstellar habitable zone

text: According to extended habitable zone concept, planetary-mass objects with atmospheres capable of inducing sufficient radiative forcing could possess liquid water farther out from the Sun. Such objects could include those whose atmospheres contain a high component of greenhouse gas and terrestrial planets much more massive than Earth (super-Earth class planets), that have retained atmospheres with surface pressures of up to 100 kbar. There are no examples of such objects in the Solar System to study; not enough is known about the nature of atmospheres of these kinds of extrasolar objects, and their position in the habitable zone cannot determine the net temperature effect of such atmospheres including induced albedo, anti-greenhouse or other possible heat sources.


title: Circumstellar habitable zone

text: For reference, the average distance from the Sun of some major bodies within the various estimates of the habitable zone is: Mercury, 0.39 AU; Venus, 0.72 AU; Earth, 1.00 AU; Mars, 1.52 AU; Vesta, 2.36 AU; Ceres and Pallas, 2.77 AU; Jupiter, 5.20 AU; Saturn, 9.58 AU. In the most conservative estimates, only Earth lies within the zone; in the most permissive estimates, even Saturn at perihelion, or Mercury at aphelion, might be included.


title: Circumstellar habitable zone

text: Astronomers use stellar flux and the inverse-square law to extrapolate circumstellar habitable zone models created for the Solar System to other stars. For example, according to Kopparapu's habitable zone estimate, although the Solar System has a circumstellar habitable zone centered at 1.34 AU from the Sun, a star with 0.25 times the luminosity of the Sun would have a habitable zone centered at formula_1, or 0.5, the distance from the star, corresponding to a distance of 0.67 AU. Various complicating factors, though, including the individual characteristics of stars themselves, mean that extrasolar extrapolation of the CHZ concept is more complex.


title: Circumstellar habitable zone

text: Some scientists argue that the concept of a circumstellar habitable zone is actually limited to stars in certain types of systems or of certain spectral types. Binary systems, for example, have circumstellar habitable zones that differ from those of single-star planetary systems, in addition to the orbital stability concerns inherent with a three-body configuration. If the Solar System were such a binary system, the outer limits of the resulting circumstellar habitable zone could extend as far as 2.4 AU.


title: Circumstellar habitable zone

text: With regard to spectral types, Zoltán Balog proposes that O-type stars cannot form planets due to the photoevaporation caused by their strong ultraviolet emissions. Studying ultraviolet emissions, Andrea Buccino found that only 40% of stars studied (including the Sun) had overlapping liquid water and ultraviolet habitable zones. Stars smaller than the Sun, on the other hand, have distinct impediments to habitability. For example, Michael Hart proposed that only main-sequence stars of spectral class K0 or brighter could offer habitable zones, an idea which has evolved in modern times into the concept of a tidal locking radius for red dwarfs. Within this radius, which is coincidental with the red-dwarf habitable zone, it has been suggested that the volcanism caused by tidal heating could cause a "tidal Venus" planet with high temperatures and no hospitable environment to life.


title: Circumstellar habitable zone

text: Others maintain that circumstellar habitable zones are more common, and that it is indeed possible for water to exist on planets orbiting cooler stars. Climate modelling from 2013 supports the idea that red dwarf stars can support planets with relatively constant temperatures over their surfaces in spite of tidal locking. Astronomy professor Eric Agol argues that even white dwarfs may support a relatively brief habitable zone through planetary migration. At the same time, others have written in similar support of semi-stable, temporary habitable zones around brown dwarfs. Also, a habitable zone in the outer parts of stellar systems may exist during the pre-main-sequence phase of stellar evolution, especially around M-dwarfs, potentially lasting for billion-year timescales.


title: Circumstellar habitable zone

text: Circumstellar habitable zones change over time with stellar evolution. For example, hot O-type stars, which may remain on the main sequence for fewer than 10 million years, would have rapidly changing habitable zones not conducive to the development of life. Red dwarf stars, on the other hand, which can live for hundreds of billions of years on the main sequence, would have planets with ample time for life to develop and evolve. Even while stars are on the main sequence, though, their energy output steadily increases, pushing their habitable zones farther out; our Sun, for example, was 75% as bright in the Archaean as it is now, and in the future, continued increases in energy output will put Earth outside the Sun's habitable zone, even before it reaches the red giant phase. In order to deal with this increase in luminosity, the concept of a "continuously habitable zone" has been introduced. As the name suggests, the continuously habitable zone is a region around a star in which planetary-mass bodies can sustain liquid water for a given period. Like the general circumstellar habitable zone, the continuously habitable zone of a star is divided into a conservative and extended region.


title: Circumstellar habitable zone

text: In red dwarf systems, gigantic stellar flares which could double a star's brightness in minutes and huge starspots which can cover 20% of the star's surface area, have the potential to strip an otherwise habitable planet of its atmosphere and water. As with more massive stars, though, stellar evolution changes their nature and energy flux, so by about 1.2 billion years of age, red dwarfs generally become sufficiently constant to allow for the development of life.


title: Circumstellar habitable zone

text: Once a star has evolved sufficiently to become a red giant, its circumstellar habitable zone will change dramatically from its main-sequence size. For example, the Sun is expected to engulf the previously habitable Earth as a red giant. However, once a red giant star reaches the horizontal branch, it achieves a new equilibrium and can sustain a new circumstellar habitable zone, which in the case of the Sun would range from 7 to 22 AU. At such stage, Saturn's moon Titan would likely be habitable in Earth's temperature sense. Given that this new equilibrium lasts for about 1 Gyr, and because life on Earth emerged by 0.7 Gyr from the formation of the Solar System at latest, life could conceivably develop on planetary mass objects in the habitable zone of red giants. However, around such a helium-burning star, important life processes like photosynthesis could only happen around planets where the atmosphere has carbon dioxide, as by the time a solar-mass star becomes a red giant, planetary-mass bodies would have already absorbed much of their free carbon dioxide. Moreover, as Ramirez and Kaltenegger (2016) showed, intense stellar winds would completely remove the atmospheres of such smaller planetary bodies, rendering them uninhabitable anyway. Thus, Titan would not be habitable even after the Sun becomes a red giant. Nevertheless, life need not originate during this stage of stellar evolution for it to be detected. Once the star becomes a red giant, and the habitable zone extends outward, the icy surface would melt, forming a temporary atmosphere that can be searched for signs of life that may have been thriving before the start of the red giant stage.


title: Circumstellar habitable zone

text: A planet's atmospheric conditions influence its ability to retain heat, so that the location of the habitable zone is also specific to each type of planet: desert planets (also known as dry planets), with very little water, will have less water vapor in the atmosphere than Earth and so have a reduced greenhouse effect, meaning that a desert planet could maintain oases of water closer to its star than Earth is to the Sun. The lack of water also means there is less ice to reflect heat into space, so the outer edge of desert-planet habitable zones is further out.


title: Circumstellar habitable zone

text: A planet cannot have a hydrosphere—a key ingredient for the formation of carbon-based life—unless there is a source for water within its stellar system. The origin of water on Earth is still not completely understood; possible sources include the result of impacts with icy bodies, outgassing, mineralization, leakage from hydrous minerals from the lithosphere, and photolysis. For an extrasolar system, an icy body from beyond the frost line could migrate into the habitable zone of its star, creating an ocean planet with seas hundreds of kilometers deep such as GJ 1214 b or Kepler-22b may be.


title: Circumstellar habitable zone

text: Maintenance of liquid surface water also requires a sufficiently thick atmosphere. Possible origins of terrestrial atmospheres are currently theorised to outgassing, impact degassing and ingassing. Atmospheres are thought to be maintained through similar processes along with biogeochemical cycles and the mitigation of atmospheric escape. In a 2013 study led by Italian astronomer Giovanni Vladilo, it was shown that the size of the circumstellar habitable zone increased with greater atmospheric pressure. Below an atmospheric pressure of about 15 millibars, it was found that habitability could not be maintained because even a small shift in pressure or temperature could render water unable to form as a liquid.


title: Circumstellar habitable zone

text: Although traditional definitions of the habitable zone assume that carbon dioxide and water vapor are the most important greenhouse gases (as they are on the Earth), a study led by Ramses Ramirez and co-author Lisa Kaltenegger has shown that the size of the habitable zone is greatly increased if prodigious volcanic outgassing of hydrogen is also included along with the carbon dioxide and water vapor. The outer edge in the Solar System would extend out as far as 2.4 AU in that case. Similar increases in the size of the habitable zone were computed for other stellar systems. An earlier study by Ray Pierrehumbert and Eric Gaidos had eliminated the CO-HO concept entirely, arguing that young planets could accrete many tens to hundreds of bars of hydrogen from the protoplanetary disc, providing enough of a greenhouse effect to extend the solar system outer edge to 10 AU. In this case, though, the hydrogen is not continuously replenished by volcanism and is lost within millions to tens-of-millions of years.


title: Circumstellar habitable zone

text: In the case of planets orbiting in the CHZs of red dwarf stars, the extremely close distances to the stars cause tidal locking, an important factor in habitability. For a tidally locked planet, the sidereal day is as long as the orbital period, causing one side to permanently face the host star and the other side to face away. In the past, such tidal locking was thought to cause extreme heat on the star-facing side and bitter cold on the opposite side, making many red dwarf planets uninhabitable; however, three-dimensional climate models in 2013 showed that the side of a red dwarf planet facing the host star could have extensive cloud cover, increasing its bond albedo and reducing significantly temperature differences between the two sides.


title: Circumstellar habitable zone

text: Planetary-mass natural satellites have the potential to be habitable as well. However, these bodies need to fulfill additional parameters, in particular being located within the circumplanetary habitable zones of their host planets. More specifically, moons need to be far enough from their host giant planets that they are not transformed by tidal heating into volcanic worlds like Io, but must remain within the Hill radius of the planet so that they are not pulled out of the orbit of their host planet. Red dwarfs that have masses less than 20% of that of the Sun cannot have habitable moons around giant planets, as the small size of the circumstellar habitable zone would put a habitable moon so close to the star that it would be stripped from its host planet. In such a system, a moon close enough to its host planet to maintain its orbit would have tidal heating so intense as to eliminate any prospects of habitability.


title: Circumstellar habitable zone

text: A planetary object that orbits a star with high orbital eccentricity may spend only some of its year in the CHZ and experience a large variation in temperature and atmospheric pressure. This would result in dramatic seasonal phase shifts where liquid water may exist only intermittently. It is possible that subsurface habitats could be insulated from such changes and that extremophiles on or near the surface might survive through adaptions such as hibernation (cryptobiosis) and/or hyperthermostability. Tardigrades, for example, can survive in a dehydrated state temperatures between and . Life on a planetary object orbiting outside CHZ might hibernate on the cold side as the planet approaches the apastron where the planet is coolest and become active on approach to the periastron when the planet is sufficiently warm.


title: Circumstellar habitable zone

text: A 2015 review concluded that the exoplanets Kepler-62f, Kepler-186f and Kepler-442b were likely the best candidates for being potentially habitable. These are at a distance of 990, 490 and 1,120 light-years away, respectively. Of these, Kepler-186f is closest in size to Earth with 1.2 times Earth's radius, and it is located towards the outer edge of the habitable zone around its red dwarf star. Among nearest terrestrial exoplanet candidates, Tau Ceti e is 11.9 light-years away. It is in the inner edge of its solar system's habitable zone, giving it an estimated average surface temperature of .


title: Circumstellar habitable zone

text: Studies that have attempted to estimate the number of terrestrial planets within the circumstellar habitable zone tend to reflect the availability of scientific data. A 2013 study by Ravi Kumar Kopparapu put "η", the fraction of stars with planets in the CHZ, at 0.48, meaning that there may be roughly 95–180 billion habitable planets in the Milky Way. However, this is merely a statistical prediction; only a small fraction of these possible planets have yet been discovered.


title: Circumstellar habitable zone

text: Previous studies have been more conservative. In 2011, Seth Borenstein concluded that there are roughly 500 million habitable planets in the Milky Way. NASA's Jet Propulsion Laboratory 2011 study, based on observations from the "Kepler" mission, raised the number somewhat, estimating that about "1.4 to 2.7 percent" of all stars of spectral class F, G, and K are expected to have planets in their CHZs.


title: Circumstellar habitable zone

text: The first discoveries of extrasolar planets in the CHZ occurred just a few years after the first extrasolar planets were discovered. However, these early detections were all gas giant sized, and many in eccentric orbits. Despite this, studies indicate the possibility of large, Earth-like moons around these planets supporting liquid water.