title: High-speed rail

text: China has the largest network of high-speed railways in the world. it encompassed over of high-speed rail or over two-thirds of the world's total. It is also the world's busiest with an annual ridership of over 1.44 billion in 2016 and 2.01 billion in 2018, more than 60% of total passenger rail volume. By the end of 2018, cumulative passengers delivered by high speed railway trains was reported to be over 9 billion. According to "Railway Gazette International", select trains between Beijing South to Nanjing South on the Beijing–Shanghai high-speed railway have the fastest average operating speed in the world at .


title: High-speed rail

text: The improved mobility and interconnectivity created by these new high-speed rail lines has generated a whole new high-speed commuter market around some urban areas. Commutes via high-speed rail to and from surrounding Hebei and Tianjin into Beijing have become increasingly common, likewise are between the cities surrounding Shanghai, Shenzhen and Guangzhou.


title: High-speed rail

text: A , entirely underground express rail link connects Hong Kong West Kowloon railway station near Kwun Chung to the border with Chinese mainland, where the railway continues onwards to Shenzhen's Futian station. A depot and the stabling sidings are located in Shek Kong. Commercial operations have been suspended since early 2020 due to the coronavirus outbreak. Parts of the West Kowloon station are no longer under the jurisdiction of Hong Kong to facilitate co-location of border clearance.


title: High-speed rail

text: Indonesia has one high-speed rail line under construction, the Jakarta–Bandung high-speed rail line, which will allow trains to reach up to 350 km/h.


title: High-speed rail

text: In Japan, the Shinkansen was the first bullet train and reaches a cumulative ridership of 6 billion passengers with zero passenger fatalities due to operational accidents (as of 2003), now it is second largest high speed rail in Asia.


title: High-speed rail

text: Since its opening in 2004, KTX has transferred over 360 million passengers until April 2013, and now Asia's third largest. For any transportation involving travel above , the KTX secured a market share of 57% over other modes of transport, which is by far the largest.


title: High-speed rail

text: Taiwan has a single north–south high-speed line, Taiwan high-speed rail. It is approximately long, along the west coast of Taiwan from the national capital Taipei to the southern city of Kaohsiung. The construction was managed by Taiwan high-speed rail Corporation and the total cost of the project was US$18 billion. The private company operates the line fully, and the system is based primarily on Japan's Shinkansen technology.


title: High-speed rail

text: Eight initial stations were built during the construction of the high-speed rail system: Taipei, Banqiao, Taoyuan, Hsinchu, Taichung, Chiayi, Tainan, and Zuoying (Kaohsiung). The line now has 12 total stations (Nangang, Taipei, Banqiao, Taoyuan, Hsinchu, Miaoli, Taichung, Changhua, Yunlin, Chiayi, Tainan and Zuoying) as of August 2018.


title: High-speed rail

text: Uzbekistan has a single high-speed rail line, the Tashkent–Samarkand high-speed rail line, which allows trains to reach up to 250 km/h. There are also electrified extensions at lower speeds to Bukhara and Dehkanabad.


title: High-speed rail

text: In November 2007, the Moroccan government decided to undertake the construction of a high-speed rail line between the economic capital Casablanca and Tangier, one of the largest harbour cities on the Strait of Gibraltar. The line will also serve the capital Rabat and Kenitra. The first section of the line, Kenitra–Tangier high-speed rail line, was completed in 2018.


title: High-speed rail

text: Plans in Saudi Arabia to begin service on a high-speed line consist of a phased opening starting with the route from Medina to King Abdullah Economic City followed up with the rest of the line to Mecca the following year. The Haramain high-speed railway opened in 2018.


title: High-speed rail

text: The Turkish State Railways started building high-speed rail lines in 2003. The first section of the line, between Ankara and Eskişehir, was inaugurated on 13 March 2009. It is a part of the Istanbul to Ankara high-speed rail line. A subsidiary of Turkish State Railways, Yüksek Hızlı Tren is the sole commercial operator of high-speed trains in Turkey.


title: High-speed rail

text: The construction of three separate high-speed lines from Ankara to Istanbul, Konya and Sivas, as well as taking an Ankara–İzmir line to the launch stage, form part of the Turkish Ministry of Transport's strategic aims and targets. Turkey plans to construct a network of high-speed lines in the early part of the 21st century, targeting a network of high-speed lines by 2013 and a network by 2023.


title: High-speed rail

text: In Europe, several nations are interconnected with cross-border high-speed rail, such as London-Paris, Paris-Brussel-Rotterdam, Madrid-Perpignan, and other future connecting projects exist.


title: High-speed rail

text: Market segmentation has principally focused on the business travel market. The French original focus on business travellers is reflected by the early design of the TGV trains. Pleasure travel was a secondary market; now many of the French extensions connect with vacation beaches on the Atlantic and Mediterranean, as well as major amusement parks and also the ski resorts in France and Switzerland. Friday evenings are the peak time for TGVs ("train à grande vitesse"). The system lowered prices on long-distance travel to compete more effectively with air services, and as a result some cities within an hour of Paris by TGV have become commuter communities, increasing the market while restructuring land use.


title: High-speed rail

text: On the Paris–Lyon service, the number of passengers grew sufficiently to justify the introduction of double-decker coaches. Later high-speed rail lines, such as the LGV Atlantique, the LGV Est, and most high-speed lines in France, were designed as feeder routes branching into conventional rail lines, serving a larger number of medium-sized cities.


title: High-speed rail

text: Germany's first high-speed lines ran north–south, for historical reasons, and later developed east–west after German unification. In the early 1900s, Germany became the first country to run a prototype electric train at speeds in excess of 200 km/h, and during the 1930s several steam and diesel trains achieved revenue speeds of 160 km/h in daily service. The InterCityExperimental briefly held the world speed record for a steel-wheel-on-steel-rails vehicle during the 1980s. The InterCityExpress entered revenue service in 1991 and serves purpose-built high-speed lines (), upgraded legacy lines (), and unmodified legacy lines. Lufthansa, Germany's flag carrier, has entered into a codeshare agreement with Deutsche Bahn where ICEs run as "feeder flights" bookable with a Lufthansa flight number under the AIRail program.


title: High-speed rail

text: During the 1920s and 1930s, Italy was one of the first countries to develop the technology for high-speed rail. The country constructed the "Direttissime" railways connecting major cities on dedicated electrified high-speed track (although at speeds lower to what today would be considered high-speed rail) and developed the fast ETR 200 trainset. After the Second World War and the fall of the fascist regime, interest in high-speed rail dwindled, with the successive governments considering it too costly and developing the tilting Pendolino, to run at medium-high speed (up to ) on conventional lines, instead. The only exception was the "Direttissima" between Florence and Rome, but it was not conceived to be part of a high-speed line on a large scale.


title: High-speed rail

text: A true dedicated high-speed rail network was developed during the 1980s and the 1990s, and of high-speed rail were fully operational by 2010. Frecciarossa services are operated with ETR 500 and ETR1000 non-tilting trains at 25kVAC, 50 Hz power. The operational speed of the service is .


title: High-speed rail

text: Over 100 million passengers used the Frecciarossa from the service introduction up to the first months of 2012. The high-speed rail system serves about 20 billion passenger-km per year as of 2016.


title: High-speed rail

text: Nuovo Trasporto Viaggiatori, the world's first private open-access operator of high-speed rail, is operative in Italy since 2012.


title: High-speed rail

text: As of 2015, Norway's fastest trains have a commercial top speed of and the FLIRT trains may attain . A velocity of is permitted on the Gardermoen Line, which links the Gardermoen airport to Oslo and a part of the main line northwards to Trondheim.


title: High-speed rail

text: The existing Saint Petersburg–Moscow Railway can operate at maximum speeds of 250 km/h, and the Helsinki-Saint Petersburg railway capable of a maximum of 200 km/h.


title: High-speed rail

text: Future areas include freight lines, such as the Trans-Siberian Railway in Russia, which would allow 3-day Far East to Europe service for freight, potentially fitting in between the months by ship and hours by air.


title: High-speed rail

text: Spain has built an extensive high-speed rail network, with a length of (2021), the longest in Europe. It uses standard gauge as opposed to the Iberian gauge used in most of the national railway network, meaning that the high-speed tracks are separated and not shared with local trains or freight. Although standard gauge is the norm for Spanish high-speed rail, since 2011 there exists a regional high-speed service running on Iberian gauge with special trains that connects the cities of Ourense, Santiago de Compostela, A Coruña, and Vigo in northwestern Spain. Connections to the French network exist since 2013, with direct trains from Paris to Barcelona. Although on the French side, conventional speed tracks are used from Perpignan to Montpellier.


title: High-speed rail

text: High-speed north–south freight lines in Switzerland are under construction, avoiding slow mountainous truck traffic, and lowering labour costs. The new lines, in particular the Gotthard Base Tunnel, are built for . But the short high-speed parts and the mix with freight will lower the average speeds. The limited size of the country gives fairly short domestic travel times anyway. Switzerland is investing money in lines on French and German soil to enable better access to the high-speed rail networks of those countries from Switzerland.


title: High-speed rail

text: The UK's fastest high-speed line (High Speed 1) connects London St Pancras with Brussels, Paris and Amsterdam through the Channel Tunnel. At speeds of up to , it is the only high-speed line in Britain with an operating speed of more than .


title: High-speed rail

text: The Great Western Main Line, South Wales Main Line, West Coast Main Line, Midland Main Line, Cross Country Route and East Coast Main Line all have maximum speed limits of in some areas. Attempts to increase speeds to on both the West Coast Main Line and East Coast Main Line have failed because the trains on those lines do not have cab signalling, which is a legal requirement in the UK for trains to be permitted to operate at speeds greater than due to the impracticality of observing lineside signals at such speeds.


title: High-speed rail

text: Amtrak's "Acela Express" (reaching ), "Northeast Regional", "Keystone Service", "Silver Star", "Vermonter" and certain MARC Penn Line express trains (the three reaching ) are currently the only high-speed services on the American continent, and all are limited to the Northeast Corridor. The "Acela Express" links Boston, New York City, Philadelphia, Baltimore, and Washington, D.C., and while "Northeast Regional" trains travel the whole of the same route, but make more station stops. All other high-speed rail services travel over portions of the route. The California High-Speed Rail project, eventually linking the 5 largest cities in California, is planned to have its first operating segment, between Merced and Bakersfield, in 2027.


title: High-speed rail

text: With high-speed rail there has been an increase in accessibility within cities. It allows for urban regeneration, accessibility in cities near and far, and efficient inter-city relationships. Better inter-city relationships lead to high-level services to companies, advanced technology, and marketing. The most important effect of HSR is the increase of accessibility due to shorter travel times. HSR lines have been used to create long-distance routes which in many cases cater to business travellers. However, there have also been short-distance routes that have revolutionised the concepts of HSR. They create commuting relationships between cities opening up more opportunities. Using both longer distance and shorter distance rail in one country allows for the best case of economic development, widening the labor and residential market of a metropolitan area and extending it to smaller cities. Therefore, HSR is highly related to urban development, it attracts offices and start-ups, induces industrial displacement, and promotes firm innovation.


title: High-speed rail

text: The KTX Incheon International Airport to Seoul Line (operates on Incheon AREX) was closed in 2018, due to a mix of issues, including poor ridership and track sharing. The AREX was not constructed as high-speed rail, resulting a cap of 150 km/h on KTX service in its section.


title: High-speed rail

text: In China, many conventional lines upgraded up to 200 km/h had high-speed services shifted to parallel high-speed lines. These lines, often passing through towns and having level crossings, are still used for local trains and freight trains. For example, all (passenger) EMU services on the Hankou–Danjiangkou railway were routed over the Wuhan–Shiyan high-speed railway on its opening to free up capacity for freight trains on the slower railway.


title: Crimean Tatars

text: Crimean Tatars () or Crimeans () are a Turkic ethnic group and nation who are an indigenous people of Crimea. The formation and ethnogenesis of Crimean Tatars occurred during the 13th–17th centuries, uniting Cumans, who appeared in Crimea in the 10th century, with other peoples who had inhabited Crimea since ancient times and gradually underwent Tatarization, including Greeks, Italians, Armenians, Goths, Sarmatians, and many others.


title: Crimean Tatars

text: Crimean Tatars constituted the majority of Crimea's population from the time of ethnogenesis until the mid-19th century, and the largest ethnic population until the end of the 19th century. Russia attempted to purge through a combination of physical violence, intimidation, forced resettlement, and legalized forms of discrimination between 1783 and 1900. Between Russia’s annexation of Crimea in 1783 and 1800, somewhere between 100,000 and 300,000 Crimean Tatars emigrated. However, this did not result in the complete eradication of Crimean Tatar cultural elements (at least not under the Romanov dynasty; however, under the Soviets, the Crimean Tatars were almost completely driven from the Crimean peninsula).Almost immediately after retaking of Crimea from Axis forces, in May 1944, the USSR State Defense Committee ordered the deportation of all of the Crimean Tatars from Crimea, including the families of Crimean Tatars who had served in the Soviet Army. The deportees were transported in trains and boxcars to Central Asia, primarily to Uzbekistan. The Crimean Tatars lost 18 to 46 percent of their population as a result of the deportations. Starting in 1967, a few were allowed to return and in 1989 the Supreme Soviet of the Soviet Union condemned the removal of Crimean Tatars from their motherland as inhumane and lawless, but only a tiny percent were able to return before the full right of return became policy in 1989.


title: Crimean Tatars

text: The European Union and international indigenous groups do not dispute their status as an indigenous people and they have been officially recognized as an indigenous people of Ukraine as of 2014. The current Russian administration considers them a "national minority", but not an indigenous people, and continues to deny that they are titular people of Crimea, even though the Soviet Union considered them indigenous before their deportation and the subsequent dissolution of the Crimean Autonomous Soviet Socialist Republic (Crimean ASSR). Today, Crimean Tatars constitute approximately 15% of the population of Crimea. There remains a Crimean Tatar diaspora in Turkey and Uzbekistan.


title: Crimean Tatars

text: The Crimean Tatars have been members of the Unrepresented Nations and Peoples Organization (UNPO) since 1991.


title: Crimean Tatars

text: In the Ukrainian census of 2001, 248,200 Ukrainian citizens identified themselves as Crimean Tatars with 98% (or about 243,400) of them living in the Autonomous Republic of Crimea. An additional 1,800 (or about 0.7%) lived in the city of Sevastopol, also on the Crimean peninsula, but outside the border of the autonomous republic.


title: Crimean Tatars

text: About 150,000 remain in exile in Central Asia, mainly in Uzbekistan. The official number of Crimean Tatars in Turkey is 150,000 with some Crimean Tatar activists estimating a figure as high as 6 million. The activists reached this number by taking one million Tatar immigrants to Turkey as a starting point and multiplying this number by the birth rate in the span of the last hundred years. Crimean Tatars in Turkey mostly live in Eskişehir Province, descendants of those who emigrated in the late 18th, 19th and early 20th centuries. The Dobruja region of Romania and Bulgaria is home to more than 27,000 Crimean Tatars, with the majority in Romania and approximately 3,000 on the Bulgarian side of the border.


title: Crimean Tatars

text: Historians suggest that inhabitants of the mountainous parts of Crimea lying to the central and southern parts (the Tats), and those of the Southern coast of Crimea (the Yalıboyu) were the direct descendants of the Pontic Greeks, Armenians, Scythians, Ostrogoths (Crimean Goths) and Kipchaks along with the Cumans while the latest inhabitants of the northern steppe represent the descendants of the Nogai Horde of the Black Sea, nominally subjects of the Crimean Khan. It is largely assumed that the Tatarization process that mostly took place in the 16th century brought a sense of cultural unity through the blending of the Greeks, Armenians, Italians and Ottoman Turks of the southern coast, Goths of the central mountains and Turkic-speaking Kipchaks and Cumans of the steppe and forming of the Crimean Tatar ethnic group. However, the Cuman language is considered the direct ancestor of the current language of the Crimean Tatars with possible incorporations of the other languages, like Crimean Gothic. The fact that Crimean Tatars' ethnogenesis took place in Crimea and consisted of several stages lasting over 2500 years is proved by genetic research showing that the gene pool of the Crimean Tatars preserved both the initial components for more than 2.5 thousand years, and later in the northern steppe regions of the Crimea.


title: Crimean Tatars

text: The Mongol conquest of the Kipchaks led to a merged society with a Mongol ruling class over a Kipchak speaking population which came to be dubbed Tatar and which eventually absorbed other ethnicities on the Crimean peninsula like Armenians, Italians, Greeks, and Goths to form the modern day Crimean Tatar people; up to the Soviet deportation, the Crimean Tatars could still differentiate among themselves between Tatar, Kipchak, Nogays, and the "Tat" descendants of Tatarized Goths and other Turkified peoples.


title: Crimean Tatars

text: The Crimean Tatars were formed as a people in Crimea and are descendants of various peoples who lived in Crimea in different historical eras. The main ethnic groups that inhabited the Crimea at various times and took part in the formation of the Crimean Tatar people are Tauri, Scythians, Sarmatians, Alans, Greeks, Goths, Bulgars, Khazars, Pechenegs, Italians and Circassians. The consolidation of this diverse ethnic conglomerate into a single Crimean Tatar people took place over the course of centuries. The connecting elements in this process were the commonality of the territory, the Turkic language and Islamic religion.


title: Crimean Tatars

text: By the end of the 15th century, the main prerequisites that led to the formation of an independent Crimean Tatar ethnic group were created: the political dominance of the Crimean Khanate was established in Crimea, the Turkic languages (Cuman-Kipchak on the territory of the khanate) became dominant, and Islam acquired the status of a state religion throughout the Peninsula. By a preponderance Cumanian population of the Crimea acquired the name "Tatars", the Islamic religion and Turkic language, and the process of consolidating the multi-ethnic conglomerate of the Peninsula began, which has led to the emergence of the Crimean Tatar people. Over several centuries, on the basis of Cuman language with a noticeable Oghuz influence, the Crimean Tatar language has developed.


title: Crimean Tatars

text: At the beginning of the 13th century, the Crimea, the majority of the population of which was already composed of a Turkic people — Cumans, became a part of the Golden Horde. The Crimean Tatars mostly adopted Islam in the 14th century and thereafter Crimea became one of the centers of Islamic civilization in Eastern Europe. In the same century, trends towards separatism appeared in the Crimean Ulus of the Golden Horde. De facto independence of the Crimea from the Golden Horde may be counted since the beginning of princess (khanum) Canike's, the daughter of the powerful Khan of the Golden Horde Tokhtamysh and the wife of the founder of the Nogai Horde Edigey, reign in the peninsula. During her reign she strongly supported Hacı Giray in the struggle for the Crimean throne until her death in 1437. Following the death of Сanike, the situation of Hacı Giray in Crimea weakened and he was forced to leave Crimea for Lithuania.


title: Crimean Tatars

text: The Crimean Tatars emerged as a nation at the time of the Crimean Khanate, an Ottoman vassal state during the 16th to 18th centuries. Russian historian, doctor of history, Professor of the Russian Academy of Sciences Ilya Zaytsev writes that analysis of historical data shows that the influence of Turkey on the policy of the Crimea was not as high as it was reported in old Turkish sources and Imperial Russian ones. The Turkic-speaking population of Crimea had mostly adopted Islam already in the 14th century, following the conversion of Ozbeg Khan of the Golden Horde. By the time of the first Russian invasion of Crimea in 1736, the Khan's archives and libraries were famous throughout the Islamic world, and under Khan Krym-Girei the city of Aqmescit was endowed with piped water, sewerage and a theatre where Molière was performed in French, while the port of Kezlev stood comparison with Rotterdam and Bakhchysarai, the capital, was described as Europe's cleanest and greenest city.


title: Crimean Tatars

text: In 1441, an embassy from the representatives of several strongest clans of the Crimea, including the Golden Horde clans Shırın and Barın and the Cumanic clan — Kıpçak, went to the Grand Duchy of Lithuania to invite Hacı Giray to rule in the Crimea. He became the founder of the Giray dynasty, which ruled until the annexation of the Crimean Khanate by Russia in 1783. Hacı I Giray was a Jochid descendant of Genghis Khan and of his grandson Batu Khan of the Golden Horde. During the reign of Meñli I Giray, Hacı's son, the army of the Great Horde that still existed then invaded the Crimea from the north, Crimean Khan won the general battle, overtaking the army of the Horde Khan in Takht-Lia, where he was killed, the Horde ceased to exist, and the Crimean Khan became the Great Khan and the successor of this state. Since then, the Crimean Khanate was among the strongest powers in Eastern Europe until the beginning of the 18th century. The Khanate officially operated as a vassal state of the Ottoman Empire, with great autonomy after 1580. At the same time, the Nogai hordes, not having their own khan, were vassals of the Crimean one, Muskovy and Polish-Lithuanian commonwealth paid annual tribute to the khan (until 1700 and 1699 respectively). In the 17th century, the Crimean Tatars helped Ukrainian Cossacks led by Bohdan Khmelnytsky in the struggle for independence, which allowed them to win several decisive victories over Polish troops.


title: Crimean Tatars

text: In 1711, when Peter I of Russia went on a campaign with all his troops (80,000) to gain access to the Black Sea, he was surrounded by the army of the Crimean Khan Devlet II Giray, finding himself in a hopeless situation. And only the betrayal of the Ottoman vizier Baltacı Mehmet Pasha allowed Peter to get out of the encirclement of the Crimean Tatars. When Devlet II Giray protested against the vizier's decision, his response was: ""You should know your Tatar affairs. The affairs of the Sublime Porte are entrusted to me. You do not have the right to interfere in them"". Treaty of the Pruth was signed, and 10 years later, Russia declared itself an empire. In 1736, the Crimean Khan Qaplan I Giray was summoned by the Turkish Sultan Ahmed III to Persia. Understanding that Russia could take advantage of the lack of troops in Crimea, Qaplan Giray wrote to the Sultan to think twice, but the Sultan was persistent. As it was expected by Qaplan Giray, in 1736 the Russian army invaded the Crimea, led by Münnich, devastated the peninsula, killed civilians and destroyed all major cities, occupied the capital, Bakhchisaray, and burnt the Khan's palace with all the archives and documents, and then left the Crimea because of the epidemic that had begun in it. One year after the same was done by another Russian general — Peter Lacy. Since then, the Crimean Khanate had not been able to recover, and its slow decline began. The Russo-Turkish War of 1768 to 1774 resulted in the defeat of the Ottomans by the Russians, and according to the Treaty of Küçük Kaynarca (1774) signed after the war, Crimea became independent and the Ottomans renounced their political right to protect the Crimean Khanate. After a period of political unrest in Crimea, Imperial Russia violated the treaty and annexed the Crimean Khanate in 1783.


title: Crimean Tatars

text: The main population of the Crimean khanate were Crimean Tatars, along with them in the Crimean khanate lived significant communities of Karaites, Italians, Armenians, Greeks, Circassians and Roma. In the early 16th century under the rule of the Crimean khans passed part of Nogays (Mangyts), who roamed outside the Crimean Peninsula, moving there during periods of drought and starvation. The majority of the population professed Islam of the Hanafi stream; part of the population – Orthodox, Monotheletism, Judaism; in the 16th century. There were small Catholic communities. The Crimean Tatar population of the Crimean Peninsula was partially exempt from taxes. The Greeks paid dzhyziya, the Italians were in a privileged position due to the partial tax relief made during the reign of Meñli Geray I. By the 18 century the population of the Crimean khanate was about 500 thousand people. The territory of the Crimean khanate was divided into Kinakanta (governorships), which consisted of Kadylyk, covering a number of settlements.


title: Crimean Tatars

text: Until the beginning of the 18th century, Crimean Nogays were known for frequent, at some periods almost annual, slave raids into Ukraine and Russia. For a long time, until the late 18th century, the Crimean Khanate maintained a massive slave trade with the Ottoman Empire and the Middle East which was one of the important factors of its economy. One of the most important trading ports and slave markets was Kefe. According to the Ottoman census of 1526, taxes on the sale and purchase of slaves accounted for 24% of the funds, levied in Ottoman Crimea for all activities. But in fact, there were always small raids committed by both Tatars and Cossacks, in both directions. The 17th century Ottoman writer and traveller Evliya Çelebi wrote that there were 920,000 Ukrainian slaves in the Crimea but only 187,000 free Muslims. However, the Ukrainian historian considers this testimony of Çelebi a myth popular among ultranationalists, pointing out that today it is known from the writings on economics that in the 17th century, the Crimea could feed no more than 500 thousand people. For comparison, according to the notes of the Consul of France to Qırım Giray khan Baron Totta, a hundred years later, in 1767, there were 4 million people living in the Crimean khanate, and in 1778, that is, just eleven years later, all the Christians were evicted from its territory by the Russian authorities, which turned out to be about 30 thousand, mostly Armenians and Greeks, and there were no Ukrainians among them. Also, according to more reliable modern sources than Evliya's data, slaves never constituted a significant part of the Crimean population. Russian professor Glagolev writes that there were 1.800.000 free Crimean Tatars in the Crimean Khanate in 1666, it also should be mentioned that a huge part of Ukraine was part of the Crimean Khanate, that is why Ukrainians could have been taken into account in the general population of the Khanate by Evliya (see Khan Ukraine).


title: Crimean Tatars

text: Some researchers estimate that more than 2 million people were captured and enslaved during the time of the Crimean Khanate. Polish historian Bohdan Baranowski assumed that in the 17th century Polish–Lithuanian Commonwealth (present-day Poland, Ukraine and Belarus) lost an average of 20,000 yearly and as many as one million in all years combined from 1500 to 1644. In retaliation, the lands of Crimean Tatars were being raided by Zaporozhian Cossacks, armed Ukrainian horsemen, who defended the steppe frontier – Wild Fields – against Tatar slave raids and often attacked and plundered the lands of Ottoman Turks and Crimean Tatars. The Don Cossacks and Kalmyk Mongols also managed to raid Crimean Tatars' land. The last recorded major Crimean raid, before those in the Russo-Turkish War (1768–74) took place during the reign of Peter the Great (1682–1725). However, Cossack raids continued after that time; Ottoman Grand Vizier complained to the Russian consul about raids to Crimea and Özi in 1761. In 1769 one last major Tatar raid, which took place during the Russo-Turkish War, saw the capture of 20,000 slaves.


title: Crimean Tatars

text: Nevertheless, some historians, including Russian historian Valery Vozgrin and Polish historian Oleksa Gayvoronsky have emphasized that the role of the slave trade in the economy of the Crimean Khanate is greatly exaggerated by modern historians, and the raiding-dependent economy is nothing but a historical myth. According to modern researches, livestock occupied a leading position in the economy of the Crimean Khanate, Crimean Khanate was one of the main wheat suppliers to the Ottoman Empire. Salt mining, viticulture and winemaking, horticulture and gardening were also developed as sources of income.


title: Crimean Tatars

text: When reading the history of the Crimean Tatars, it is necessary to take into account that the historical science about the Crimean Tatars is strongly influenced by Russian historians who have rewritten the history of the Crimean Khanate to justify the annexation of the Crimea in 1783, and, especially, then by Soviet historians who distorted the history of the Crimea to justify the 1944 deportation of the Crimean Tatars.


title: Crimean Tatars

text: The Russo-Turkish War (1768–74) resulted in the defeat of the Ottomans by the Russians, and according to the Treaty of Küçük Kaynarca (1774) signed after the war, Crimea became independent and the Ottomans renounced their political right to protect the Crimean Khanate. After a period of political unrest in Crimea, Russia violated the treaty and annexed the Crimean Khanate in 1783. After the annexation, the wealthier Tatars, who had exported wheat, meat, fish and wine to other parts of the Black Sea, began to be expelled and to move to the Ottoman Empire. Due to the oppression by the Russian administration and colonial politics of Russian Empire, the Crimean Tatars were forced to immigrate to the Ottoman Empire. Further expulsions followed in 1812 for fear of the reliability of the Tatars in the face of Napoleon's advance. Particularly, the Crimean War of 1853–1856, the laws of 1860–63, the Tsarist policy and the Russo-Turkish War (1877–78) caused an exodus of the Tatars; 12,000 boarded Allied ships in Sevastopol to escape the destruction of shelling, and were branded traitors by the Russian government. Of total Tatar population 300,000 of the Taurida Governorate about 200,000 Crimean Tatars emigrated. Many Crimean Tatars perished in the process of emigration, including those who drowned while crossing the Black Sea. In total, from 1783 till the beginning of the 20th century, at least 800 thousand Tatars left Crimea. Today the descendants of these Crimeans form the Crimean Tatar diaspora in Bulgaria, Romania and Turkey.


title: Crimean Tatars

text: Ismail Gasprali (1851–1914) was a renowned Crimean Tatar intellectual, influenced by the nationalist movements of the period, whose efforts laid the foundation for the modernization of Muslim culture and the emergence of the Crimean Tatar national identity. The bilingual Crimean Tatar-Russian newspaper "Terciman-Perevodchik" he published in 1883–1914, functioned as an educational tool through which a national consciousness and modern thinking emerged among the entire Turkic-speaking population of the Russian Empire. After the Russian Revolution of 1917 this new elite, which included Noman Çelebicihan and Cafer Seydamet Qırımer proclaimed the first democratic republic in the Islamic world, named the Crimean People's Republic on 26 December 1917. However, this republic was short-lived and abolished by the Bolshevik uprising in January 1918.


title: Crimean Tatars

text: As a part of the Russian famine of 1921 the Peninsula suffered widespread starvation. More than 100,000 Crimean Tatars starved to death, and tens of thousands of Tatars fled to Turkey or Romania. Thousands more were deported or killed during the collectivization in 1928–29. The Soviet government's "collectivization" policies led to a major nationwide famine in 1931–33. Between 1917 and 1933, 150,000 Tatars—about 50% of the population at the time—either were killed or forced out of Crimea. During Stalin's Great Purge, statesmen and intellectuals such as Veli Ibraimov and Bekir Çoban-zade were imprisoned or executed on various charges.


title: Crimean Tatars

text: In May 1944, the entire Crimean Tatar population of Crimea was exiled to Central Asia, mainly to Uzbekistan, on the orders of Joseph Stalin, the General Secretary of the Communist Party of the Soviet Union and the Chairman of the USSR State Defense Committee. Although a great number of Crimean Tatar men served in the Red Army and took part in the partisan movement in Crimea during the war, the existence of a Tatar Legion in the Nazi army and the collaboration of some Crimean Tatar religious and political leaders with Hitler during the German occupation of Crimea provided the Soviet leadership with justification for accusing the entire Crimean Tatar population of being Nazi collaborators. Some modern researchers argue that Crimea's geopolitical position fueled Soviet perceptions of Crimean Tatars as a potential threat. This belief is based in part on an analogy with numerous other cases of deportations of non-Russians from boundary territories, as well as the fact that other non-Russian populations, such as Greeks, Armenians and Bulgarians were also removed from Crimea (see ).


title: Crimean Tatars

text: All 240,000 Crimean Tatars were deported "en masse", in a form of collective punishment, on 17–18 May 1944 as "special settlers" to the Uzbek Soviet Socialist Republic and other distant parts of the Soviet Union. This event is called Sürgün in the Crimean Tatar language; the few who escaped were shot on sight or drowned in scuttled barges, and within months half their number had died of cold, hunger, exhaustion and disease. Many of them were re-located to toil as forced labourers in the Soviet GULAG system.


title: Crimean Tatars

text: Starting in 1944, Crimean Tatars lived mostly in Central Asia with the designation as "special settlers", meaning that they had few rights. "Special settlers" were forbidden from leaving small designated areas and had to frequently sign in at a commandant's office. Soviet propaganda directed towards Uzbeks depicted Crimean Tatars as threats to their homeland, and as a result there were many documented hate crimes against Crimean-Tatar civilians by Uzbek Communist loyalists. In the 1950s the "special settler" regime ended, but Crimean Tatars were still kept closely tethered to Central Asia; while other deported ethnic groups like the Chechens, Karachays, and Kalmyks were fully allowed to return to their native lands during the Khrushchev thaw, economic and political reasons combined with basic misconceptions and stereotypes about Crimean Tatars led to Moscow and Tashkent being reluctant to allow Crimean Tatars the same right of return; the same decree that rehabilitated the beforementioned deported nations and restored their national republics urged Crimean Tatars who wanted a national republic to seek "national reunification" in the Tatar ASSR in lieu of restoration of the Crimean ASSR, much to the dismay of Crimean Tatars who bore no connection to or desire to "return" to Tatarstan. Moscow's refusal to allow a return was not only based out of a desire to satisfy the new Russian settlers in Crimea, who were very hostile to the idea of a return and had been subject to lots of Tatarophobic propaganda, but for economic reasons: high productivity from Crimean Tatar workers in Central Asia meant that letting the diaspora return would take a toll on Soviet industrialization goals in Central Asia. Historians have long suspected that violent resistance to confinement in exile from Chechens led to further willingness to let them return, while the non-violent Crimean Tatar movement did not lead to any desire for Crimean Tatars to leave Central Asia. In effect, the government was punishing Crimean Tatars for being Stakhanovites while rewarding the deported nations that contributed less to the building of socialism, creating further resentment.


title: Crimean Tatars

text: A 1967 Soviet decree removed the charges against Crimean Tatars on paper while simultaneously referring to them not by their proper ethnonym but by the euphemism that eventually became standard of "citizens of Tatar nationality who formerly lived in Crimea", angering many Crimean Tatars who realized it meant they were not even seen as Crimean Tatars by the government. In addition, the Soviet government did nothing to facilitate their resettlement in Crimea and to make reparations for lost lives and confiscated property. Before the mass return in the perestroika era, Crimean Tatars made up only 1.5% of Crimea's population, since government entities at all levels took a variety of measures beyond the already-debilitating residence permit system to keep them in Central Asia.


title: Crimean Tatars

text: The abolition of the special settlement regime made it possible for Crimean Tatar rights activists to mobilize. The primary method of raising grievances with the government was petitioning. Many for the right of return gained over 100,000 signatures; although other methods of protest were occasionally used, the movement remained completely non-violent. When only a small percentage of Crimean Tatars were allowed to return to Crimea, those who were not granted residence permits would return to Crimea and try to live under the radar. However, the lack of a residence permit resulted in a second deportation for them. A last-resort method to avoid a second deportation was self-immolation, famously used by Crimean Tatar national hero Musa Mamut, one of those who moved to Crimea without a residence permit. He doused himself with gasoline and committed self-immolation in front of police trying to deport him on 23 June 1978. Mamut died of severe burns several days later, but expressed no regret for having committed self-immolation. Mamut posthumously became a symbol of Crimean Tatar resistance and nationhood, and remains celebrated by Crimean Tatars. Other notable self-immolations in the name of the Crimean Tatar right of return movement include that of Shavkat Yarullin, who fatally committed self-immolation in front of a government building in protest in October 1989, and Seidamet Balji who attempted self-immolation while being deported from Crimea in December that year but survived. Many other famous Crimean Tatars threatened government authorities with self-immolation if they continued to be ignored, including Hero of the Soviet Union Abdraim Reshidov. In the later years of the Soviet Union, Crimean Tatar activists held picket protests in Red Square.


title: Crimean Tatars

text: After a prolonged effort of lobbying by the Crimean Tatar civil rights movement, the Soviet government established a commission in 1987 to evaluate the request for the right of return, chaired by Andrey Gromyko. Gromyko's condescending attitude and failure to assure them that they would have the right of return ended up concerning members of the Crimean Tatar civil rights movement. In June 1988 he issued an official statement that rejected the request for re-establishment of a Crimean Tatar autonomy in Crimea and supported only allowing an organized return of a few more Crimean Tatars, while agreeing to allow the lower-priority requests of having more publications and school instruction in the Crimean Tatar language at the local level among areas with the deported populations. The conclusion that "no basis to renew autonomy and grant Crimean Tatars the right to return" triggered widespread protests. Less than two years after Gromyko's commission had rejected their request for autonomy and return, pogroms against the deported Meskhetian Turks were taking place in Central Asia. During the pogroms, some Crimean Tatars were targeted as well, resulting in changing attitudes towards allowing Crimean Tatars to move back to Crimea. Eventually a second commission, chaired by Gennady Yanaev and inclusive of Crimean Tatars on the board, was established in 1989 to reevaluate the issue, and it was decided that the deportation was illegal and the Crimean Tatars were granted the full right to return, revoking previous laws intended to make it as difficult as possible for Crimean Tatars to move to Crimea.


title: Crimean Tatars

text: Today, more than 250,000 Crimean Tatars have returned to their homeland, struggling to re-establish their lives and reclaim their national and cultural rights against many social and economic obstacles. One-third of them are atheists, and over half that consider themselves religious are non-observant.


title: Crimean Tatars

text: Following news of Crimea's independence referendum organized with the help of Russia on 16 March 2014, the Kurultai leadership voiced concerns of renewed persecution, as commented by a U.S. official before the visit of a UN human rights team to the peninsula. At the same time, Rustam Minnikhanov, the president of Tatarstan was dispatched to Crimea to quell Crimean Tatars' concerns and to state that "in the 23 years of Ukraine's independence the Ukrainian leaders have been using Crimean Tatars as pawns in their political games without doing them any tangible favors". The issue of Crimean Tatar persecution by Russia has since been raised regularly on an international level.


title: Crimean Tatars

text: On 18 March 2014, the day Crimea was annexed by Russia, and Crimean Tatar was "de jure" declared one of the three official languages of Crimea. It was also announced that Crimean Tatars will be required to relinquish coastal lands on which they squatted since their return to Crimea in the early 1990s and be given land elsewhere in Crimea. Crimea stated it needed the relinquished land for "social purposes", since part of this land is occupied by the Crimean Tatars without legal documents of ownership. The situation was caused by the inability of the USSR (and later Ukraine) to sell the land to Crimean Tatars at a reasonable price instead of giving back to the Tatars the land owned before deportation, once they or their descendants returned from Central Asia (mainly Uzbekistan). As a consequence, some Crimean Tatars settled as squatters, occupying land that was and is still not legally registered.


title: Crimean Tatars

text: Some Crimean Tatars fled to Mainland Ukraine due to the Crimean crisis – reportedly around 2000 by 23 March. On 29 March 2014, an emergency meeting of the Crimean Tatars representative body, the Kurultai, voted in favor of seeking "ethnic and territorial autonomy" for Crimean Tatars using "political and legal" means. The meeting was attended by the Head of the Republic of Tatarstan and the chair of the Russian Council of Muftis. Decisions as to whether the Tatars will accept Russian passports or whether the autonomy sought would be within the Russian or Ukrainian state have been deferred pending further discussion.


title: Crimean Tatars

text: After the annexation of Crimea by Russian Federation, Crimean Tatars are reportedly persecuted and discriminated by Russian authorities, including cases of torture, arbitrary detentions, forced disappearances by Russian security forces and courts.


title: Crimean Tatars

text: On 12 June 2018, Ukraine lodged a memorandum consisting of 17,500 pages of text in 29 volumes to the UN's International Court of Justice about racial discrimination against Crimean Tatars by Russian authorities in occupied Crimea and state financing of terrorism by Russian Federation in Donbas.


title: Crimean Tatars

text: Yurts or nomadic tents have traditionally played an important role in the cultural history of Crimean Tatars. There are different types of yurts; some are large and collapsible, called "terme", while others are small and non-collapsible (otav).


title: Crimean Tatars

text: On the Nowruz holiday, Crimean Tatars usually cook eggs, chicken soup, puff meat pie (kobete), halva, and sweet biscuits. Children put on masks and sing special songs under the windows of their neighbours, receiving sweets in return.


title: Crimean Tatars

text: The songs (makam) of the nomadic steppe Crimean Tatars are characterized by diatonic, melodic simplicity and brevity. The songs of mountainous and southern coastal Crimean Tatars, called , are sung with richly ornamented melodies. Household lyricism is also widespread. Occasionally, song competitions take place between young men and women during Crimean holidays and weddings. Ritual folklore includes winter greetings, wedding songs, lamentations and circular dance songs (khoran). Epic stories or destans are very popular among the Crimean Tatars, particularly the destans of "Chora batyr", "Edige", "Koroglu" and others.


title: Crimean Tatars

text: Today in use there are two types of alphabet: Cyrillic and Latin. Initially Crimean Tatars used Arabic script. In 1928 it was replaced with the Latin alphabet. Cyrillic was introduced in 1938 based on the Russian alphabet. The Cyrillic alphabet was the only official one between 1938 and 1997. All its letters coincide with those of the Russian alphabet. The 1990s saw the start of the gradual transition of the language to the new Latin alphabet based on the Turkish one.


title: Crimean Tatars

text: The traditional cuisine of the Crimean Tatars has similarities with that of Greeks, Italians, Balkan peoples, Nogays, North Caucasians, and Volga Tatars, although some national dishes and dietary habits vary between different Crimean Tatar regional subgroups; for example, fish and produce are more popular among Yaliboylu Tatar dishes while meat and dairy is more prevalent in Steppe Tatar cuisine. Many Uzbek dishes were incorporated into Crimean Tatar national cuisine during exile in Central Asia since 1944, and these dishes have become prevalent in Crimea since the return. Uzbek samsa, laghman, and (pilaf) are sold in most Tatar roadside cafes in Crimea as national dishes. In turn, some Crimean Tatar dishes, including chibureki, have been adopted by peoples outside Crimea, such as in Turkey and the North Caucasus.


title: Crimean Tatars

text: Founded by Crimean Tatar civil rights activist Yuri Osmanov, the National Movement of Crimean Tatars (NDKT) was the major opposition faction to the Dzhemilev faction during the Soviet era. The official goal of the NDKT during the Soviet era was the restoration of the Crimean ASSR under the Leninist principle of national autonomy for titular indigenous peoples in their homeland, conflicting with the desires of an independent Tatar state from the OKND, the predecessor of the Mejilis. Yuri Osmanov, founder of the organization, was highly critical of Dzhemilev, saying that the OKND, the predecessor of the Mejilis, did not sufficiently try to mend ethnic tensions in Crimea. However, the OKND decreased in popularity after Yuri Osmanov was killed.


title: Crimean Tatars

text: In 1991, the Crimean Tatar leadership founded the Kurultai, or Parliament, to act as a representative body for the Crimean Tatars which could address grievances to the Ukrainian central government, the Crimean government, and international bodies. Mejlis of the Crimean Tatar People is the executive body of the Kurultai.


title: Crimean Tatars

text: From the 1990s until October 2013, the political leader of the Crimean Tatars and the chairman of the Mejlis of the Crimean Tatar People was former Soviet dissident Mustafa Dzhemilev. Since October 2013 the chairman of the Mejlis of the Crimean Tatar People has been Refat Chubarov.


title: Crimean Tatars

text: Following the 2014 Russian annexation of Crimea, Russian authorities declared the Mejlis of the Crimean Tatar People an extremist organization, and banned it on 26 April 2016.


title: Crimean Tatars

text: In 2006, a new Crimean Tatar party in opposition to the Mejlis was founded, taking the name of the previously-defunct Milly Firqa party from the early 20th century. The party claims to be successor of the ideas of Yuri Osmanov and NDKT.


title: Crimean Tatars

text: In Romanian "Uniunea Democratica a Tatarilor Turco-Musulmani din Romania, UDTTMR" in Crimean Tatar "Romanya Müslüman Tatar Türklerĭ Demokrat Bĭrlĭgĭ, RMTTDB" is an ethnic minority political party in Romania representing the Tatar community.


title: Outer space

text: Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is . The plasma between galaxies is thought to account for about half of the baryonic (ordinary) matter in the universe, having a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is "dark energy", a type of vacuum energy that is poorly understood. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space.


title: Outer space

text: Outer space does not begin at a definite altitude above the Earth's surface. The Kármán line, an altitude of above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. Certain portions of the upper stratosphere and the mesosphere are also sometimes referred to as "near space". The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit.


title: Outer space

text: Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights. This was followed by crewed rocket flights and, then, crewed Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961. Due to the high cost of getting into space, human spaceflight has been limited to low Earth orbit and the Moon. On the other hand, uncrewed spacecraft have reached all of the known planets in the Solar System.


title: Outer space

text: Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental issues, the economic cost of putting objects, including humans, into space is very high.


title: Outer space

text: The size of the whole universe is unknown, and it might be infinite in extent. According to the Big Bang theory, the very early Universe was an extremely hot and dense state about 13.8 billion years ago which rapidly expanded. About 380,000 years later the Universe had cooled sufficiently to allow protons and electrons to combine and form hydrogen—the so-called recombination epoch. When this happened, matter and energy became decoupled, allowing photons to travel freely through the continually expanding space. Matter that remained following the initial expansion has since undergone gravitational collapse to create stars, galaxies and other astronomical objects, leaving behind a deep vacuum that forms what is now called outer space. As light has a finite velocity, this theory also constrains the size of the directly observable universe.


title: Outer space

text: The present day shape of the universe has been determined from measurements of the cosmic microwave background using satellites like the Wilkinson Microwave Anisotropy Probe. These observations indicate that the spatial geometry of the observable universe is "flat", meaning that photons on parallel paths at one point remain parallel as they travel through space to the limit of the observable universe, except for local gravity. The flat Universe, combined with the measured mass density of the Universe and the accelerating expansion of the Universe, indicates that space has a non-zero vacuum energy, which is called dark energy.


title: Outer space

text: Estimates put the average energy density of the present day Universe at the equivalent of 5.9 protons per cubic meter, including dark energy, dark matter, and baryonic matter (ordinary matter composed of atoms). The atoms account for only 4.6% of the total energy density, or a density of one proton per four cubic meters. The density of the Universe is clearly not uniform; it ranges from relatively high density in galaxies—including very high density in structures within galaxies, such as planets, stars, and black holes—to conditions in vast voids that have much lower density, at least in terms of visible matter. Unlike matter and dark matter, dark energy seems not to be concentrated in galaxies: although dark energy may account for a majority of the mass-energy in the Universe, dark energy's influence is 5 orders of magnitude smaller than the influence of gravity from matter and dark matter within the Milky Way.


title: Outer space

text: Outer space is the closest known approximation to a perfect vacuum. It has effectively no friction, allowing stars, planets, and moons to move freely along their ideal orbits, following the initial formation stage. The deep vacuum of intergalactic space is not devoid of matter, as it contains a few hydrogen atoms per cubic meter. By comparison, the air humans breathe contains about 10 molecules per cubic meter. The low density of matter in outer space means that electromagnetic radiation can travel great distances without being scattered: the mean free path of a photon in intergalactic space is about 10 km, or 10 billion light years. In spite of this, extinction, which is the absorption and scattering of photons by dust and gas, is an important factor in galactic and intergalactic astronomy.


title: Outer space

text: Stars, planets, and moons retain their atmospheres by gravitational attraction. Atmospheres have no clearly delineated upper boundary: the density of atmospheric gas gradually decreases with distance from the object until it becomes indistinguishable from outer space. The Earth's atmospheric pressure drops to about Pa at of altitude, compared to 100,000 Pa for the International Union of Pure and Applied Chemistry (IUPAC) definition of standard pressure. Above this altitude, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar wind. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather.


title: Outer space

text: The temperature of outer space is measured in terms of the kinetic activity of the gas, as it is on Earth. The radiation of outer space has a different temperature than the kinetic temperature of the gas, meaning that the gas and radiation are not in thermodynamic equilibrium. All of the observable universe is filled with photons that were created during the Big Bang, which is known as the cosmic microwave background radiation (CMB). (There is quite likely a correspondingly large number of neutrinos called the cosmic neutrino background.) The current black body temperature of the background radiation is about . The gas temperatures in outer space can vary widely. For example, the temperature in the Boomerang Nebula is 1 K, while the solar corona reaches temperatures over 1.2–2.6 million K.


title: Outer space

text: Magnetic fields have been detected in the space around just about every class of celestial object. Star formation in spiral galaxies can generate small-scale dynamos, creating turbulent magnetic field strengths of around 5–10 μG. The Davis–Greenstein effect causes elongated dust grains to align themselves with a galaxy's magnetic field, resulting in weak optical polarization. This has been used to show ordered magnetic fields exist in several nearby galaxies. Magneto-hydrodynamic processes in active elliptical galaxies produce their characteristic jets and radio lobes. Non-thermal radio sources have been detected even among the most distant, high-z sources, indicating the presence of magnetic fields.


title: Outer space

text: Outside a protective atmosphere and magnetic field, there are few obstacles to the passage through space of energetic subatomic particles known as cosmic rays. These particles have energies ranging from about 10 eV up to an extreme 10 eV of ultra-high-energy cosmic rays. The peak flux of cosmic rays occurs at energies of about 10 eV, with approximately 87% protons, 12% helium nuclei and 1% heavier nuclei. In the high energy range, the flux of electrons is only about 1% of that of protons. Cosmic rays can damage electronic components and pose a health threat to space travelers. According to astronauts, like Don Pettit, space has a burned/metallic odor that clings to their suits and equipment, similar to the scent of an arc welding torch.


title: Outer space

text: Despite the harsh environment, several life forms have been found that can withstand extreme space conditions for extended periods. Species of lichen carried on the ESA BIOPAN facility survived exposure for ten days in 2007. Seeds of "Arabidopsis thaliana" and "Nicotiana tabacum" germinated after being exposed to space for 1.5 years. A strain of "Bacillus subtilis" has survived 559 days when exposed to low Earth orbit or a simulated martian environment. The lithopanspermia hypothesis suggests that rocks ejected into outer space from life-harboring planets may successfully transport life forms to another habitable world. A conjecture is that just such a scenario occurred early in the history of the Solar System, with potentially microorganism-bearing rocks being exchanged between Venus, Earth, and Mars.


title: Outer space

text: Even at relatively low altitudes in the Earth's atmosphere, conditions are hostile to the human body. The altitude where atmospheric pressure matches the vapor pressure of water at the temperature of the human body is called the Armstrong line, named after American physician Harry G. Armstrong. It is located at an altitude of around . At or above the Armstrong line, fluids in the throat and lungs boil away. More specifically, exposed bodily liquids such as saliva, tears, and liquids in the lungs boil away. Hence, at this altitude, human survival requires a pressure suit, or a pressurized capsule.


title: Outer space

text: Out in space, sudden exposure of an unprotected human to very low pressure, such as during a rapid decompression, can cause pulmonary barotrauma—a rupture of the lungs, due to the large pressure differential between inside and outside the chest. Even if the subject's airway is fully open, the flow of air through the windpipe may be too slow to prevent the rupture. Rapid decompression can rupture eardrums and sinuses, bruising and blood seep can occur in soft tissues, and shock can cause an increase in oxygen consumption that leads to hypoxia.


title: Outer space

text: As a consequence of rapid decompression, oxygen dissolved in the blood empties into the lungs to try to equalize the partial pressure gradient. Once the deoxygenated blood arrives at the brain, humans lose consciousness after a few seconds and die of hypoxia within minutes. Blood and other body fluids boil when the pressure drops below 6.3 kPa, and this condition is called ebullism. The steam may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Ebullism is slowed by the pressure containment of blood vessels, so some blood remains liquid. Swelling and ebullism can be reduced by containment in a pressure suit. The Crew Altitude Protection Suit (CAPS), a fitted elastic garment designed in the 1960s for astronauts, prevents ebullism at pressures as low as 2 kPa. Supplemental oxygen is needed at to provide enough oxygen for breathing and to prevent water loss, while above pressure suits are essential to prevent ebullism. Most space suits use around 30–39 kPa of pure oxygen, about the same as on the Earth's surface. This pressure is high enough to prevent ebullism, but evaporation of nitrogen dissolved in the blood could still cause decompression sickness and gas embolisms if not managed.


title: Outer space

text: Humans evolved for life in Earth gravity, and exposure to weightlessness has been shown to have deleterious effects on human health. Initially, more than 50% of astronauts experience space motion sickness. This can cause nausea and vomiting, vertigo, headaches, lethargy, and overall malaise. The duration of space sickness varies, but it typically lasts for 1–3 days, after which the body adjusts to the new environment. Longer-term exposure to weightlessness results in muscle atrophy and deterioration of the skeleton, or spaceflight osteopenia. These effects can be minimized through a regimen of exercise. Other effects include fluid redistribution, slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, and puffiness of the face.


title: Outer space

text: During long-duration space travel, radiation can pose an acute health hazard. Exposure to high-energy, ionizing cosmic rays can result in fatigue, nausea, vomiting, as well as damage to the immune system and changes to the white blood cell count. Over longer durations, symptoms include an increased risk of cancer, plus damage to the eyes, nervous system, lungs and the gastrointestinal tract. On a round-trip Mars mission lasting three years, a large fraction of the cells in an astronaut's body would be traversed and potentially damaged by high energy nuclei. The energy of such particles is significantly diminished by the shielding provided by the walls of a spacecraft and can be further diminished by water containers and other barriers. The impact of the cosmic rays upon the shielding produces additional radiation that can affect the crew. Further research is needed to assess the radiation hazards and determine suitable countermeasures.


title: Outer space

text: There is no clear boundary between Earth's atmosphere and space, as the density of the atmosphere gradually decreases as the altitude increases. There are several standard boundary designations, namely:


title: Outer space

text: In 2009, scientists reported detailed measurements with a Supra-Thermal Ion Imager (an instrument that measures the direction and speed of ions), which allowed them to establish a boundary at above Earth. The boundary represents the midpoint of a gradual transition over tens of kilometers from the relatively gentle winds of the Earth's atmosphere to the more violent flows of charged particles in space, which can reach speeds well over .


title: Outer space

text: The Outer Space Treaty provides the basic framework for international space law. It covers the legal use of outer space by nation states, and includes in its definition of "outer space", the Moon, and other celestial bodies. The treaty states that outer space is free for all nation states to explore and is not subject to claims of national sovereignty, calling outer space the "province of all mankind". This status as a common heritage of mankind has been used, though not without opposition, to enforce the right to access and shared use of outer space for all nations equally, particularly non-spacefaring nations. It also prohibits the development of nuclear weapons in outer space. The treaty was passed by the United Nations General Assembly in 1963 and signed in 1967 by the USSR, the United States of America and the United Kingdom. As of 2017, 105 state parties have either ratified or acceded to the treaty. An additional 25 states signed the treaty, without ratifying it.


title: Outer space

text: Since 1958, outer space has been the subject of multiple United Nations resolutions. Of these, more than 50 have been concerning the international co-operation in the peaceful uses of outer space and preventing an arms race in space. Four additional space law treaties have been negotiated and drafted by the UN's Committee on the Peaceful Uses of Outer Space. Still, there remains no legal prohibition against deploying conventional weapons in space, and anti-satellite weapons have been successfully tested by the US, USSR, China, and in 2019, India. The 1979 Moon Treaty turned the jurisdiction of all heavenly bodies (including the orbits around such bodies) over to the international community. The treaty has not been ratified by any nation that currently practices human spaceflight.


title: Outer space

text: In 1976, eight equatorial states (Ecuador, Colombia, Brazil, Congo, Zaire, Uganda, Kenya, and Indonesia) met in Bogotá, Colombia. With their "Declaration of the First Meeting of Equatorial Countries", or "the Bogotá Declaration", they claimed control of the segment of the geosynchronous orbital path corresponding to each country. These claims are not internationally accepted.


title: Outer space

text: A spacecraft enters orbit when its centripetal acceleration due to gravity is less than or equal to the centrifugal acceleration due to the horizontal component of its velocity. For a low Earth orbit, this velocity is about ; by contrast, the fastest piloted airplane speed ever achieved (excluding speeds achieved by deorbiting spacecraft) was in 1967 by the North American X-15.


title: Outer space

text: To achieve an orbit, a spacecraft must travel faster than a sub-orbital spaceflight. The energy required to reach Earth orbital velocity at an altitude of is about 36 MJ/kg, which is six times the energy needed merely to climb to the corresponding altitude. Spacecraft with a perigee below about are subject to drag from the Earth's atmosphere, which decreases the orbital altitude. The rate of orbital decay depends on the satellite's cross-sectional area and mass, as well as variations in the air density of the upper atmosphere. Below about , decay becomes more rapid with lifetimes measured in days. Once a satellite descends to , it has only hours before it vaporizes in the atmosphere. The escape velocity required to pull free of Earth's gravitational field altogether and move into interplanetary space is about .


title: Outer space

text: Space is a partial vacuum: its different regions are defined by the various atmospheres and "winds" that dominate within them, and extend to the point at which those winds give way to those beyond. Geospace extends from Earth's atmosphere to the outer reaches of Earth's magnetic field, whereupon it gives way to the solar wind of interplanetary space. Interplanetary space extends to the heliopause, whereupon the solar wind gives way to the winds of the interstellar medium. Interstellar space then continues to the edges of the galaxy, where it fades into the intergalactic void.


title: Outer space

text: Near-Earth space is the region of outer space above the Kármán line, from low Earth orbits out to geostationary orbits. This region includes the major orbits for artificial satellites and is the site of most of humanity's space activity. The region has seen high levels of space pollution, mainly in the form of space debris, threatening any space activity in this region.


title: Outer space

text: Geospace is a region of outer space near Earth that includes the upper atmosphere and magnetosphere. The Van Allen radiation belts lie within the geospace. The outer boundary of geospace is the magnetopause, which forms an interface between the Earth's magnetosphere and the solar wind. The inner boundary is the ionosphere. The variable space-weather conditions of geospace are affected by the behavior of the Sun and the solar wind; the subject of geospace is interlinked with heliophysics—the study of the Sun and its impact on the planets of the Solar System.


title: Outer space

text: The day-side magnetopause is compressed by solar-wind pressure—the subsolar distance from the center of the Earth is typically 10 Earth radii. On the night side, the solar wind stretches the magnetosphere to form a magnetotail that sometimes extends out to more than 100–200 Earth radii. For roughly four days of each month, the lunar surface is shielded from the solar wind as the Moon passes through the magnetotail.


title: Outer space

text: Geospace is populated by electrically charged particles at very low densities, the motions of which are controlled by the Earth's magnetic field. These plasmas form a medium from which storm-like disturbances powered by the solar wind can drive electrical currents into the Earth's upper atmosphere. Geomagnetic storms can disturb two regions of geospace, the radiation belts and the ionosphere. These storms increase fluxes of energetic electrons that can permanently damage satellite electronics, interfering with shortwave radio communication and GPS location and timing. Magnetic storms can also be a hazard to astronauts, even in low Earth orbit. They also create aurorae seen at high latitudes in an oval surrounding the geomagnetic poles.


title: Outer space

text: Although it meets the definition of outer space, the atmospheric density within the first few hundred kilometers above the Kármán line is still sufficient to produce significant drag on satellites. This region contains material left over from previous crewed and uncrewed launches that are a potential hazard to spacecraft. Some of this debris re-enters Earth's atmosphere periodically.


title: Outer space

text: Cislunar space is a region outside of Earth that includes lunar orbit, the Moon's orbital space around Earth and the Lagrange points. xGeo space is a concept used by the US to refer to space of High Earth Orbits, ranging from beyond geosynchronous orbit (GEO) at approximately , out to the L2 Earth-Moon Lagrange point at . This is located beyond the orbit of the Moon and therefore includes cislunar space.


title: Outer space

text: The region where Earth's gravity well remains dominant against gravitational perturbations from the Sun is the planet's Hill sphere. This includes all space from the Earth to a distance of roughly 1% of the mean distance from Earth to the Sun, or . Beyond Earth's Hill sphere extends along Earth's orbital path its orbital and co-orbital space. This space is co-populated by groups of co-orbital Near-Earth Objects (NEOs), such as horseshoe librators and Earth trojans, with some NEOs at times becoming temporary satellites and quasi-moons to Earth.


title: Outer space

text: Deep space is defined by the United States government and others as any region beyond cislunar space. The International Telecommunication Union responsible for radio communication, including with satellites, defines the beginning of deep space at , which is about five times the Moon's orbital distance.


title: Outer space

text: Interplanetary space is defined by the solar wind, a continuous stream of charged particles emanating from the Sun that creates a very tenuous atmosphere (the heliosphere) for billions of kilometers into space. This wind has a particle density of 5–10 protons/cm and is moving at a velocity of . Interplanetary space extends out to the heliopause where the influence of the galactic environment starts to dominate over the magnetic field and particle flux from the Sun. The distance and strength of the heliopause varies depending on the activity level of the solar wind. The heliopause in turn deflects away low-energy galactic cosmic rays, with this modulation effect peaking during solar maximum.


title: Outer space

text: The volume of interplanetary space is a nearly total vacuum, with a mean free path of about one astronomical unit at the orbital distance of the Earth. This space is not completely empty, and is sparsely filled with cosmic rays, which include ionized atomic nuclei and various subatomic particles. There is also gas, plasma and dust, small meteors, and several dozen types of organic molecules discovered to date by microwave spectroscopy. A cloud of interplanetary dust is visible at night as a faint band called the zodiacal light.


title: Outer space

text: Interplanetary space contains the magnetic field generated by the Sun. There are also magnetospheres generated by planets such as Jupiter, Saturn, Mercury and the Earth that have their own magnetic fields. These are shaped by the influence of the solar wind into the approximation of a teardrop shape, with the long tail extending outward behind the planet. These magnetic fields can trap particles from the solar wind and other sources, creating belts of charged particles such as the Van Allen radiation belts. Planets without magnetic fields, such as Mars, have their atmospheres gradually eroded by the solar wind.


title: Outer space

text: Interstellar space is the physical space within a galaxy beyond the influence each star has upon the encompassed plasma. The contents of interstellar space are called the interstellar medium. Approximately 70% of the mass of the interstellar medium consists of lone hydrogen atoms; most of the remainder consists of helium atoms. This is enriched with trace amounts of heavier atoms formed through stellar nucleosynthesis. These atoms are ejected into the interstellar medium by stellar winds or when evolved stars begin to shed their outer envelopes such as during the formation of a planetary nebula. The cataclysmic explosion of a supernova generates an expanding shock wave consisting of ejected materials that further enrich the medium. The density of matter in the interstellar medium can vary considerably: the average is around 10 particles per m, but cold molecular clouds can hold 10–10 per m.


title: Outer space

text: A number of molecules exist in interstellar space, as can tiny 0.1 μm dust particles. The tally of molecules discovered through radio astronomy is steadily increasing at the rate of about four new species per year. Large regions of higher density matter known as molecular clouds allow chemical reactions to occur, including the formation of organic polyatomic species. Much of this chemistry is driven by collisions. Energetic cosmic rays penetrate the cold, dense clouds and ionize hydrogen and helium, resulting, for example, in the trihydrogen cation. An ionized helium atom can then split relatively abundant carbon monoxide to produce ionized carbon, which in turn can lead to organic chemical reactions.


title: Outer space

text: The local interstellar medium is a region of space within 100 parsecs (pc) of the Sun, which is of interest both for its proximity and for its interaction with the Solar System. This volume nearly coincides with a region of space known as the Local Bubble, which is characterized by a lack of dense, cold clouds. It forms a cavity in the Orion Arm of the Milky Way galaxy, with dense molecular clouds lying along the borders, such as those in the constellations of Ophiuchus and Taurus. (The actual distance to the border of this cavity varies from 60 to 250 pc or more.) This volume contains about 10–10 stars and the local interstellar gas counterbalances the astrospheres that surround these stars, with the volume of each sphere varying depending on the local density of the interstellar medium. The Local Bubble contains dozens of warm interstellar clouds with temperatures of up to 7,000 K and radii of 0.5–5 pc.


title: Outer space

text: When stars are moving at sufficiently high peculiar velocities, their astrospheres can generate bow shocks as they collide with the interstellar medium. For decades it was assumed that the Sun had a bow shock. In 2012, data from Interstellar Boundary Explorer (IBEX) and NASA's Voyager probes showed that the Sun's bow shock does not exist. Instead, these authors argue that a subsonic bow wave defines the transition from the solar wind flow to the interstellar medium. A bow shock is the third boundary of an astrosphere after the termination shock and the astropause (called the heliopause in the Solar System).


title: Outer space

text: Intergalactic space is the physical space between galaxies. Studies of the large-scale distribution of galaxies show that the Universe has a foam-like structure, with groups and clusters of galaxies lying along filaments that occupy about a tenth of the total space. The remainder forms huge voids that are mostly empty of galaxies. Typically, a void spans a distance of 7–30 megaparsecs.


title: Outer space

text: Surrounding and stretching between galaxies, there is a rarefied plasma that is organized in a galactic filamentary structure. This material is called the intergalactic medium (IGM). The density of the IGM is 5–200 times the average density of the Universe. It consists mostly of ionized hydrogen; i.e. a plasma consisting of equal numbers of electrons and protons. As gas falls into the intergalactic medium from the voids, it heats up to temperatures of 10 K to 10 K, which is high enough so that collisions between atoms have enough energy to cause the bound electrons to escape from the hydrogen nuclei; this is why the IGM is ionized. At these temperatures, it is called the warm–hot intergalactic medium (WHIM). (Although the plasma is very hot by terrestrial standards, 10 K is often called "warm" in astrophysics.) Computer simulations and observations indicate that up to half of the atomic matter in the Universe might exist in this warm–hot, rarefied state. When gas falls from the filamentary structures of the WHIM into the galaxy clusters at the intersections of the cosmic filaments, it can heat up even more, reaching temperatures of 10 K and above in the so-called intracluster medium (ICM).


title: Outer space

text: In 350 BCE, Greek philosopher Aristotle suggested that "nature abhors a vacuum", a principle that became known as the "horror vacui". This concept built upon a 5th-century BCE ontological argument by the Greek philosopher Parmenides, who denied the possible existence of a void in space. Based on this idea that a vacuum could not exist, in the West it was widely held for many centuries that space could not be empty. As late as the 17th century, the French philosopher René Descartes argued that the entirety of space must be filled.


title: Outer space

text: In ancient China, the 2nd-century astronomer Zhang Heng became convinced that space must be infinite, extending well beyond the mechanism that supported the Sun and the stars. The surviving books of the Hsüan Yeh school said that the heavens were boundless, "empty and void of substance". Likewise, the "sun, moon, and the company of stars float in the empty space, moving or standing still".


title: Outer space

text: The Italian scientist Galileo Galilei knew that air had mass and so was subject to gravity. In 1640, he demonstrated that an established force resisted the formation of a vacuum. It would remain for his pupil Evangelista Torricelli to create an apparatus that would produce a partial vacuum in 1643. This experiment resulted in the first mercury barometer and created a scientific sensation in Europe. The French mathematician Blaise Pascal reasoned that if the column of mercury was supported by air, then the column ought to be shorter at higher altitude where the air pressure is lower. In 1648, his brother-in-law, Florin Périer, repeated the experiment on the Puy de Dôme mountain in central France and found that the column was shorter by three inches. This decrease in pressure was further demonstrated by carrying a half-full balloon up a mountain and watching it gradually expand, then contract upon descent.


title: Outer space

text: In 1650, German scientist Otto von Guericke constructed the first vacuum pump: a device that would further refute the principle of "horror vacui". He correctly noted that the atmosphere of the Earth surrounds the planet like a shell, with the density gradually declining with altitude. He concluded that there must be a vacuum between the Earth and the Moon.


title: Outer space

text: Back in the 15th century, German theologian Nicolaus Cusanus speculated that the Universe lacked a center and a circumference. He believed that the Universe, while not infinite, could not be held as finite as it lacked any bounds within which it could be contained. These ideas led to speculations as to the infinite dimension of space by the Italian philosopher Giordano Bruno in the 16th century. He extended the Copernican heliocentric cosmology to the concept of an infinite Universe filled with a substance he called aether, which did not resist the motion of heavenly bodies. English philosopher William Gilbert arrived at a similar conclusion, arguing that the stars are visible to us only because they are surrounded by a thin aether or a void. This concept of an aether originated with ancient Greek philosophers, including Aristotle, who conceived of it as the medium through which the heavenly bodies move.


title: Outer space

text: The concept of a Universe filled with a luminiferous aether retained support among some scientists until the early 20th century. This form of aether was viewed as the medium through which light could propagate. In 1887, the Michelson–Morley experiment tried to detect the Earth's motion through this medium by looking for changes in the speed of light depending on the direction of the planet's motion. The null result indicated something was wrong with the concept. The idea of the luminiferous aether was then abandoned. It was replaced by Albert Einstein's theory of special relativity, which holds that the speed of light in a vacuum is a fixed constant, independent of the observer's motion or frame of reference.


title: Outer space

text: The first professional astronomer to support the concept of an infinite Universe was the Englishman Thomas Digges in 1576. But the scale of the Universe remained unknown until the first successful measurement of the distance to a nearby star in 1838 by the German astronomer Friedrich Bessel. He showed that the star system 61 Cygni had a parallax of just 0.31 arcseconds (compared to the modern value of 0.287″). This corresponds to a distance of over 10 light years. In 1917, Heber Curtis noted that novae in spiral nebulae were, on average, 10 magnitudes fainter than galactic novae, suggesting that the former are 100 times further away. The distance to the Andromeda Galaxy was determined in 1923 by American astronomer Edwin Hubble by measuring the brightness of cepheid variables in that galaxy, a new technique discovered by Henrietta Leavitt. This established that the Andromeda galaxy, and by extension all galaxies, lay well outside the Milky Way.


title: Outer space

text: The modern concept of outer space is based on the "Big Bang" cosmology, first proposed in 1931 by the Belgian physicist Georges Lemaître. This theory holds that the universe originated from a very dense form that has since undergone continuous expansion.


title: Outer space

text: The earliest known estimate of the temperature of outer space was by the Swiss physicist Charles É. Guillaume in 1896. Using the estimated radiation of the background stars, he concluded that space must be heated to a temperature of 5–6 K. British physicist Arthur Eddington made a similar calculation to derive a temperature of 3.18 K in 1926. German physicist Erich Regener used the total measured energy of cosmic rays to estimate an intergalactic temperature of 2.8 K in 1933. American physicists Ralph Alpher and Robert Herman predicted 5 K for the temperature of space in 1948, based on the gradual decrease in background energy following the then-new Big Bang theory. The modern measurement of the cosmic microwave background is about 2.7K.


title: Outer space

text: The term "outward space" was used in 1842 by the English poet Lady Emmeline Stuart-Wortley in her poem "The Maiden of Moscow". The expression "outer space" was used as an astronomical term by Alexander von Humboldt in 1845. It was later popularized in the writings of H. G. Wells in 1901. The shorter term "space" is older, first used to mean the region beyond Earth's sky in John Milton's "Paradise Lost" in 1667. "Spaceborne" denotes existing in outer space, especially if carried by a spacecraft; similarly, "space-based" means based in outer space or using space technology.


title: Outer space

text: For most of human history, space was explored by observations made from the Earth's surface—initially with the unaided eye and then with the telescope. Before reliable rocket technology, the closest that humans had come to reaching outer space was through balloon flights. In 1935, the U.S. Explorer II crewed balloon flight reached an altitude of . This was greatly exceeded in 1942 when the third launch of the German A-4 rocket climbed to an altitude of about . In 1957, the uncrewed satellite Sputnik 1 was launched by a Russian R-7 rocket, achieving Earth orbit at an altitude of . This was followed by the first human spaceflight in 1961, when Yuri Gagarin was sent into orbit on Vostok 1. The first humans to escape low Earth orbit were Frank Borman, Jim Lovell and William Anders in 1968 on board the U.S. Apollo 8, which achieved lunar orbit and reached a maximum distance of from the Earth.


title: Outer space

text: The first spacecraft to reach escape velocity was the Soviet "Luna 1", which performed a fly-by of the Moon in 1959. In 1961, "Venera 1" became the first planetary probe. It revealed the presence of the solar wind and performed the first fly-by of Venus, although contact was lost before reaching Venus. The first successful planetary mission was the 1962 fly-by of Venus by Mariner 2. The first fly-by of Mars was by Mariner 4 in 1964. Since that time, uncrewed spacecraft have successfully examined each of the Solar System's planets, as well their moons and many minor planets and comets. They remain a fundamental tool for the exploration of outer space, as well as for observation of the Earth. In August 2012, "Voyager 1" became the first man-made object to leave the Solar System and enter interstellar space.


title: Outer space

text: The absence of air makes outer space an ideal location for astronomy at all wavelengths of the electromagnetic spectrum. This is evidenced by the spectacular pictures sent back by the Hubble Space Telescope, allowing light from more than 13 billion years ago—almost to the time of the Big Bang—to be observed. Not every location in space is ideal for a telescope. The interplanetary zodiacal dust emits a diffuse near-infrared radiation that can mask the emission of faint sources such as extrasolar planets. Moving an infrared telescope out past the dust increases its effectiveness. Likewise, a site like the Daedalus crater on the far side of the Moon could shield a radio telescope from the radio frequency interference that hampers Earth-based observations.


title: Outer space

text: Uncrewed spacecraft in Earth orbit are an essential technology of modern civilization. They allow direct monitoring of weather conditions, relay long-range communications like television, provide a means of precise navigation, and allow remote sensing of the Earth. The latter role serves a wide variety of purposes, including tracking soil moisture for agriculture, prediction of water outflow from seasonal snow packs, detection of diseases in plants and trees, and surveillance of military activities.


title: Outer space

text: The deep vacuum of space could make it an attractive environment for certain industrial processes, such as those requiring ultraclean surfaces. Like asteroid mining, space manufacturing would require a large financial investment with little prospect of immediate return. An important factor in the total expense is the high cost of placing mass into Earth orbit: $–$ per kg, according to a 2006 estimate (allowing for inflation since then). The cost of access to space has declined since 2013. Partially reusable rockets such as the Falcon 9 have lowered access to space below 3500 dollars per kilogram. With these new rockets the cost to send materials into space remains prohibitively high for many industries. Proposed concepts for addressing this issue include, fully reusable launch systems, non-rocket spacelaunch, momentum exchange tethers, and space elevators.


title: Outer space

text: Interstellar travel for a human crew remains at present only a theoretical possibility. The distances to the nearest stars mean it would require new technological developments and the ability to safely sustain crews for journeys lasting several decades. For example, the Daedalus Project study, which proposed a spacecraft powered by the fusion of deuterium and helium-3, would require 36 years to reach the "nearby" Alpha Centauri system. Other proposed interstellar propulsion systems include light sails, ramjets, and beam-powered propulsion. More advanced propulsion systems could use antimatter as a fuel, potentially reaching relativistic velocities.


title: Outer space

text: In addition to astronomy and space travel, the ultracold temperature of outer space can be used as a renewable cooling technology for various applications on Earth through passive daytime radiative cooling, which enhances longwave infrared (LWIR) thermal radiation heat transfer on the Earth's surface through the infrared window into outer space to lower ambient temperatures. It became possible with the discovery to suppress solar heating with photonic metamaterials.


title: Rhea (mythology)

text: Rhea or Rheia (; Ancient Greek: Ῥέα or Ῥεία ) is a mother goddess in ancient Greek religion and Greek mythology, the Titaness daughter of the earth goddess Gaia and the sky god Uranus, himself a son of Gaia. She is the older sister of Cronus, who was also her consort, and the mother of the five eldest Olympian gods Hestia, Demeter, Hera, Poseidon and Zeus, and the king of the Underworld, Hades.


title: Rhea (mythology)

text: When Cronus learnt that he was destined to be overthrown by one of his children like his father was before him, he swallowed all the children Rhea bore as soon as they were born. When Rhea had her sixth and final child, Zeus, she spirited him away and hid him in Crete, giving Cronus a rock to swallow instead, thus saving her youngest son who would go on to challenge his father's rule and rescue the rest of his siblings. Following Zeus' defeat of Cronus and the rise of the Olympian gods into power, Rhea withdraws her role as the queen of the gods to become a supporting figure on Mount Olympus. She has some roles and myths in the new Olympian era; she attended the birth of her grandson Apollo and raised her other grandson Dionysus, after Persephone was abducted by Hades, Rhea was sent to Demeter by Zeus, while in the myth of Pelops, she brings back the unfortunate youth to life after he was slain.


title: Rhea (mythology)

text: In early traditions, she is known as "the mother of gods" and therefore is strongly associated with Gaia and Cybele, who have similar functions. The classical Greeks saw her as the mother of the Olympian gods and goddesses. The Romans identified her with Magna Mater (their form of Cybele), and the Goddess Ops.


title: Rhea (mythology)

text: Some ancient etymologists derived "" () (by metathesis) from (, 'ground', 'earth'); the same is suggested also by modern scholars, such as Robert Graves.


title: Rhea (mythology)

text: A different tradition, embodied in Plato and in Chrysippus, connected the word with ("", 'flow, discharge'), which is what "A Greek–English Lexicon" supports. Alternatively, the name "Rhea" may be connected with words for the pomegranate: (), and later ().


title: Rhea (mythology)

text: Rhea is the sister of the Titans (Oceanus, Crius, Hyperion, Iapetus, Coeus, Themis, Theia, Phoebe, Tethys, Mnemosyne, Cronus and sometimes Dione), the Cyclopes, the Hecatoncheires, the Giants, the Meliae, the Erinyes, and the half-sister of Aphrodite (in some versions), Typhon, Python, Pontus, Thaumas, Phorcys, Nereus, Eurybia and Ceto.


title: Rhea (mythology)

text: According to Hesiod, Rhea had six children with Cronus: Hestia, Demeter, Hera, Hades, Poseidon, and Zeus in that order. The philosopher Plato recounts that Rhea, Cronus and Phorcys were the eldest children of Oceanus and Tethys.


title: Rhea (mythology)

text: According to the Orphic myths, Zeus wanted to marry his mother Rhea. After Rhea refused to marry him, Zeus turned into a snake and raped her. She had Persephone with Zeus.


title: Rhea (mythology)

text: Rhea was born to the earth goddess Gaia and the sky god Uranus, one of their twelve (or thirteen) Titan children. According to Hesiod, Uranus imprisoned all his children, while Apollodorus states he only imprisoned the Cyclopes and the Hecatoncheires, not the Titans. With the help of Gaia, the youngest child, Cronus, overthrew his father, became king in his place, freed his siblings, and took his sister Rhea to wife. Ophion and Eurynome, a daughter of Oceanus, were said to have ruled snowy Mount Olympus in the early age. Rhea and Cronus fought them, and threw them into the waves of the Ocean, thus becoming rulers in their place. Rhea, skilled in wrestling, battled Eurynome specifically.


title: Rhea (mythology)

text: Gaia and Uranus told Cronus that just as he had overthrown his own father and become ruler of the cosmos, he was destined to be overcome by his own child; so as each of his children was born, Cronus swallowed them. Rhea, Uranus and Gaia devised a plan to save the last of them, Zeus. Rhea gave birth to Zeus in a cavern on the island of Crete, and gave Cronus a stone wrapped in swaddling clothes, which he promptly swallowed; Rhea hid her infant son Zeus in a cave on Mount Ida. Her attendants, the warrior-like Kouretes and Dactyls, acted as a bodyguard for the infant Zeus, helping to conceal his whereabouts from his father. In some accounts, by the will of Rhea a golden dog guarded a goat which offered her udder and gave nourishment to the infant Zeus. Later on, Zeus changed the goat into an immortal among the stars while the golden dog that guarded the sacred spot in Crete was stolen by Pandareus.""


title: Rhea (mythology)

text: In an obscure version, attested only on the east frieze of a temple at Lagina, the goddess of crossroads Hecate assisted Rhea in saving Zeus from his father. The frieze shows Hecate presenting to Cronus the swaddled stone while the real infant is being whisked away in safety.


title: Rhea (mythology)

text: While Zeus was still an infant hidden in Crete, Rhea caught her husband Cronus with his mistress the nymph Philyra in the act; Cronus then transformed into a horse and galloped away, in order not to be seen by his wife.


title: Rhea (mythology)

text: In some accounts, Rhea along with Metis gave Cronus the potion that made him disgorge the children he had eaten.


title: Rhea (mythology)

text: Following Zeus' ascension, Rhea withdrew from spotlight as she was no longer queen of gods, but remained an ally of her children and their families.


title: Rhea (mythology)

text: In some traditions, Rhea disapproved of her children Hera and Zeus getting married, so the two had to elope in order to be together. Rhea was present in the birth of her grandson Apollo, along with many other goddesses, the most notable exceptions being Hera and Eileithyia, the goddess of childbirth, whose absence left Leto in terrible agony. Rhea was said to be a goddess who eased childbirth for women.


title: Rhea (mythology)

text: After Demeter reunited with her daughter Persephone, Zeus sent Rhea to persuade Demeter to return to Olympus and rejoin the gods.