ejaasaari/simplewiki-2025-04-01 huggingface dataset:
A natural satellite in astronomy is a smaller body which moves around a larger body. The smaller body is held in orbit by gravitation. The term is often used for moons which go around planets, and it is also used for small galaxies which orbit larger galaxies. Bodies which orbit planets are called moons. They vary in size. The Earth has only one moon. Some other planets have many moons, and some have none. When people write just ""the" moon", they are usually talking about the moon of the Earth. Earth's moon is written with a capital letter, "Moon". The Latin word for the moon is "luna", which is why the adjective used to talk about the moon is "lunar". For example, lunar eclipse. Anything that goes around a planet is called a satellite. Moons are natural satellites. People also use rockets to send machines into orbit around the Earth. These machines are called artificial (man-made) satellites. Earth's moon. Moons do not make their own light. We can see the Earth's moon because it acts like a mirror, and reflects the light of the Sun. The same half of the moon faces toward Earth at all times, no matter where it moves. This effect is called tidal locking. But different parts of the moon are lit up by the Sun, so it looks different at different times of the month. This change as seen from Earth is called the phases of the moon, or lunar phases. A moon's cycle is the time the moon takes to change from looking very bright and round to looking very small and thin, and then back to bright and round again. In the case of the Earth's moon, this is about four weeks. It does this about 13 times in one year. The moon's cycle is about 28 days, a bit shorter than a calendar month. The Apollo 11 mission helped Neil Armstrong and Buzz Aldrin become the first people to walk on the Moon. They did this on July 20, 1969. Orbits. The orbit of a moon or other satellite is affected by two forces: gravity, and the centripetal force. For example, the Earth's moon is kept in orbit by the gravitational pull from
Gravity, or gravitation is one of the fundamental forces of the universe. It is an attraction, or pull, between any two objects with mass. We discuss it here in three parts: Some physicists think gravity is caused by gravitons, but they are still unsure. Everyday gravity. Weight vs mass. In everyday talk, we say things fall because the Earth's gravity pulls on them. We talk as if our weight was a "given". Actually, weight changes when the pull of gravity changes. The Moon's pull of gravity is about one sixth smaller than Earth. So any object on the Moon weighs one sixth of its weight on Earth. What does not change is the amount of matter in an object. That is called conservation of mass. On Earth, mass and weight are the same for most purposes, though a sensitive gravimeter can detect the difference. The difference can be very different on other extraterrestrial objects such as the moon, and other planets. From this we learn two things. The Earth has mass. Every particle of matter has mass. So the Earth pulls on every object and person, and they pull on the Earth. This pulling force is called "gravity" and it gives weight. Gravity vs gravitation. These words mean almost the same thing in everyday use. Sometimes scientists use "gravity" for the force that pulls objects towards each other, and "gravitation" for the theory about the attraction. Gravitational theory. Galileo. According to one of his students, Galileo did a famous experiment about gravity where he dropped balls from the Tower of Pisa. He later rolled balls down inclines. With these experiments, Galileo showed that gravitation accelerates all objects at the same rate regardless of weight. Kepler. Johannes Kepler studied the motion of planets. In 1609 and 1616 he published his three laws governing the shape of their orbits and their speed along those orbits, but did not discover why they moved that way. Newton. In 1687, English mathematician Isaac Newton wrote the "Principia". In this book, he wrote about the inverse-square law of gravitation. Newton, following an idea that had long been discussed by others, said that the closer
Centripetal acceleration is a force that acts on a body that revolves around a centre of a circular path. This force keeps the body in circular motion. Newton's first law is that a moving object will continue in its motion in a straight path unless acted on by an external force.  When you hold a rope with an object attached to it, and spin it in a circular motion around the hand of the person holding the rope, the rope becomes tight and keeps the body from flying away. This force acts towards the center of motion, not away from it.  An object changes direction, but may maintain a constant speed, if acted upon by a centripetal acceleration. In such a case, we know from its angular frequency that formula_1. From Newton's second law we know that force equals mass times acceleration. Here acceleration is the negative of the radius coming from the centre of the circular motion. formula_2  In this formula, think that the centripetal force and the centripetal momentum are the same thing because they are both measured in Newtons.  If, however, the angular frequency is not constant (as might be the case in a roller-coaster ride) then formula_3 does vary with respect to time. Here  formula_4  Thus  formula_5  as formula_6 and formula_7 , which we know from the angular frequency. Geometric proof for uniform circular motion. In the figure to the right we define the displacement vector formula_8 to represent motion in a circle. The magnitude of formula_8 is denoted as formula_10 and represents the radius of the particle's orbit.
A treaty is a written agreement between two or more parties, which may be countries or other important groups, about any subject. Treaties usually settle or avoid disputes. Countries may agree to end a war or to declare war on a common enemy by promising to come to the aid of another country if it is attacked. They may allow allow each other's citizens or merchandise to cross borders freely, such as the European Union, which is the result of treaties between most countries in Europe. In general, treaties are usually used to settle disputes, or to avoid disputes.
Luxembourg (officially called the Grand Duchy of Luxembourg (, , ) is a landlocked country in Western Europe.  It is a small country by land area. In 2023, its population was 660,809, making it one of Europe's most densely populated countries.  It was one of the first countries in the European Union. It is also a member of the Benelux. The countries next to Luxembourg are Belgium, Germany, and France. The main language is Luxembourgish but French and German is also spoken there.  History. In 963, Luxembourg was founded. Sigefroid, Count of Ardennes, came to own the ruins of an old Roman fort called "Castellum Lucilinburhuc" ("Little Castle") from the monks of the Abbey of St. Maximin in Trier. In 1354, the emperor Charles IV made Luxembourg a duchy. In 1443, Luxembourg was captured by Philip of Burgundy. In, 1795, after the French revolution Luxembourg was taken over by France. It became a département of France. In 1815, Luxembourg became a grand duchy. It was ruled by the king of the Netherlands. From 1815 to 1866, Luxembourg became a member of the German Confederation. In 1890, after the death of William III, Luxembourg passed to the House of Nassau-Weilburg. Between 1914 to 1918, Luxembourg was conquered by Germany during World War I. In 1940, the Germans returned during World War II, and in 1942 Luxembourg became part of the Third Reich. In 1944, Luxembourg became independent in September because the United States Army arrived. In 1945, Luxembourg joined the United Nations. In 1957, Luxembourg became one of the first six members of the European Economic Community. In 2020, Luxembourg became the first country in the world to make all public transport free to use. Politics. Luxembourg is a parliamentary democracy lead by a constitutional monarch. Under the constitution of 1868, executive power is in the hands of the Governor and the cabinet, which consists of several other ministers
Baden-Württemberg (, ; Alemannic German: "Baade-Wiirdebäärg") is a federal state ("Bundesland") in the southwestern region of Germany. It is the third largest German state by total area (after Bavaria and Lower Saxony) with a size of nearly 35,752 km² and population (after North Rhine-Westphalia and Bavaria) with over 11 million people as of 2017. It shares borders to the east with the state of Bavaria, to the north with the states of Hesse and Rhineland-Palatinate, to the west with the country of France (along the river Rhine), and to the south with the countries of Switzerland and Austria. Its biggest cities are Stuttgart, the capital, Mannheim, and Karlsruhe. The Minister President is Winfried Kretschmann of the party "Alliance '90/The Greens". In 2017, Baden-Württemberg ranked 2 on the Human Development Index (HDI) among all states in Germany. History. In 1952, the three states of Baden, Württemberg-Baden and Württemberg-Hohenzollern joined to found Baden-Württemberg. Politics. The Minister President is the chief of the government of Baden-Württemberg. The government is made up of ministers and state secretaries. The CDU was the main political party in the state between 1953 and 2011, the Ministers President have all been members of the CDU. Between the years 1972 and 1992, the members of the Landtag of Baden-Württemberg were mostly members of the CDU. But the state is also a stronghold of the "Grünen" which were founded in the early 1980s in Karlsruhe. The election results of the Grünen in Baden-Württemberg have always been above the election average for the party in Germany. Since 2016 there have been 5 parties represented in the Landtag of Baden-Württemberg: List of Ministers
Vienna (; ; Central Austro-Bavarian: "Wean" ; Viennese German and Austrian German: "Wian" ) is the capital and largest city of Austria. It is also one of Austria's nine states. It is in the east of the country on the river Danube. More than 1,800,000 people live there (2016). It is an administrative district ("Bundesland") of its own. Before World War I, it was the capital of the Austro-Hungarian Empire. Its centre is a UNESCO World Heritage Site. Name. In regard to the etymology of the city's name, scholars are not in agreement. Some claim that the name comes from "vedunia", meaning "forest stream"; From that word, came the Old High German word "uuenia" ("wenia" in modern writing), and the New High German word "wien" and its dialectal variant "wean". History. The history of the city goes back to the Roman Empire. The Romans started a military camp called Vindobona. The camp was in today's first district on the Danube river. The name came from the Celts, so there was probably a Celtic settlement before the Roman invasion. The Romans stayed until the 5th century. In medieval times, the settlement was still in use. The present name was mentioned in 881 in the Salzburger Annalen, where a battle "ad weniam" is mentioned. In 976 the House of Babenberg became rulers of the area. They made Vienna their capital in 1155. Vienna was already an important city. In 1156, Austria became a Duchy, and Vienna was where the Duke who ruled the Duchy lived. In 1221, Vienna got municipal rights. It Is the second oldest city in Austria (Enns, in Upper Austria, is the oldest). In 1278, the Duchy came to the Habsburg family. Rudolf IV started the university in 1365 and while he was duke the nave of the Gothic St. Stephan's Cathedral was built. Quarrels within the Hapsburg family caused an economic decline in
1925 (MCMXXV) was a common year starting on Thursday in the Gregorian calendar, the 1925th year of the Common Era (CE) and "Anno Domini" (AD) designations, .
A telescope (from the Ancient Greek τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos) makes astronomical objects appear closer to the naked eye. It is an important tool for astronomy that gathers light and directs it to a single point. Some do this with curved mirrors, some with curved lenses, and some with both. Telescopes make distant things look bigger, brighter and closer. Galileo was the first person to use a telescope for astronomy, but he did not invent them. The first telescope was invented in the Netherlands in 1608. Some telescopes, not mainly used for astronomy, are "binoculars," "camera lenses", or "spyglasses". When telescopes are used with just your eye, an eyepiece has to be used. These use two or more smaller lenses to magnify an image. Without an eyepiece, an eye cannot focus the image. When a telescope is used with a camera or other special scientific tools, eyepiece lenses are not needed. The bigger the aperture (mirror) the more light the telescope collects. It makes faint objects appear clearer. Most big telescopes for astronomy are made to study very carefully things that are already known. A few are made for searching, such as for unknown asteroids or extrasolar planets. Most big telescopes are made to be used with a CCD (Charge-Coupled Devices) camera instead of just the eye. This is called "Astrophotography". A Go-to telescope is needed to track Deep Sky objects and is placed on an Equatorial Mount for the axis to point towards Polaris, this is called polar alignment. Telescopes can be used by normal people too, not just scientists. These are amateur telescopes, and they are usually smaller, and they don't cost too much for an amateur to buy. Some of the most popular amateur telescopes are Dobsonians, a type of Newtonian telescope. The word "telescope" is usually used for light human eyes can see, but there are telescopes for wavelengths we cannot
A homonym is a word that has more than one meaning. For example, "right" means moral, the opposite of left, and a personal freedom. Definition: one of a group of words that share the same spelling and/or pronunciation but have different meanings. The point is that homonyms are either homophones (they sound the same) or homographs (they look the same) or both.
"Not to be confused with principle." A principal is a person who is in charge of something. The person is usually in charge of a school, or a research project, or a business.
Peru is a country in South America. The capital is Lima. The ruins of Machu Picchu, the Andes mountains, and the source of the Amazon River are all found in Peru. Peru is bordered to the north by Ecuador and Colombia, to the east by Brazil, to the south by Chile, and to the southeast by Bolivia. Peru is a representative democratic republic divided into 25 regions and over 33 million people live in it. Peruvian territory was home to the Norte Chico civilization, one of the oldest in the world, and to the Inca Empire, the largest state in Pre-Columbian America. The Spanish Empire conquered the region in the 16th century and established a Viceroyalty, which included most of its South American colonies. After achieving independence in 1821. Peru suffered a terrible guerrilla war in the 1980s. The communist (Maoist) Shining Path tried to take over the country. But after the leader of the group was captured in 1992, Shining Path was not a threat anymore. During the 1990s, it was ruled by President Alberto Fujimori. During this time, the economy of Peru got better, and it became easier to start a company or operate a business. After Fujimori, Alejandro Toledo was elected President, and then Alan Garcia, who was President from 1985 to 1990, was elected again in 2006. Ollanta Humala was elected President in 2011 and Pedro Pablo Kuczynski was elected President in 2016. In March 2018, Kuczynski resigned following political scandals and Vice President Martín Vizcarra was sworn-in as the next president. Economy and tourism. Peru's most important exports, products that it sells to other countries, are fish, gold and other metals, oil, coffee, sugar, and cotton. Also, the food in Peru is very diverse, including typical dishes like Ceviche and Broiled Chicken. Tourists from other countries like to come to Peru because of the history and also to enjoy nature. Many people come to climb mountains in the Cordillera Blanca in the Ancash
The Federal Republic of Germany (FRG) has 16 states (). The biggest is Bavaria and the smallest is Bremen. Most of them were created after the Second World War. Some states have historical roots from the early Middle Ages. State creation since 1949: Population and area in km² as of November 2014:
Munich ( ; ; ) is the third biggest city of Germany (after Berlin and Hamburg), and the capital of Bavaria. It has a population of around 1,500,000. The metropolitan area of Munich includes the city itself, and all the suburbs around it, and has about 3 million people in it; whereas the metropolitan region has 6.2 million people (as of 2022). It is one of the most important centres of the economy in Germany. It has an oceanic climate ("Cfb" in the Köppen climate classification). People. The official population of Munich city proper at 310.43 km2 was 1,368,840 people with their main home there on 31st January 2009. Around 176,000 inhabitants with second homes also live inside the city limits but they are not calculated in this official census. According to some estimates that population counts around 200,000 people. The fast growing Munich urban area has 2,667,000 inhabitants (2008 estimate). Munich city with all suburbs - 12,000 km2 had 4,700,000 inhabitants. The Munich metropolitan region that covers 27,700 km2 and includes Augsburg, Ingolstadt, Landshut, Rosenheim and Landsberg has around 6,000,000 inhabitants. Munich is the 12th largest city in EU by population within the city limits and the 14th largest urban area in Europe. Its metropolitan area ranks among the largest metro areas in Europe. As of December 2008, 47.3% of Munich's residents belonged to no religious group, 38.3% are Roman Catholic, 14.0% are Lutheran Protestants and 0.3% are Jewish. There is also a small Old Catholic parish and an Episcopal Church. 1158: The settlement was founded as Munichen by Henry the Lion. 1255: the Duchy of Bavaria was split in two. Munich the dukes of Upper Bavaria lived in Munich. 1806: Munich became the capital of the Kingdom of Bavaria. 1923: Beer Hall Putsch of the Nazis 193
Berlin (; ) is the capital city of Germany. It is the largest city in the European Union by population, with around 3.9 million people in 2024. Berlin residents come from about 190 different countries. The city is in the eastern part of Germany in Central Europe and is surrounded by many forests and lakes. Berlin has an area of . The rivers Havel, Dahme and Spree run through Berlin. It has a temperate climate. Berlin is home to many famous buildings and monuments, like the Siegessäule, the Brandenburger Tor, the Reichstag and the boulevard Unter den Linden. On the boulevard is the Humboldt University. The city has many nightlife options. Berlin is an important city for the history of Germany. The King of Prussia and the Emperor of Germany lived in Berlin. The government of Germany was in Berlin for many years. Bombs destroyed many buildings in the city in World War Two. The city was split into West Berlin and East Berlin after World War Two. After the Berlin Wall was built in 1961 very few people were allowed to cross from East Berlin into West Berlin. The wall divided the city until 1989 when the East German government decided to allow anyone to cross, and people decided to tear down the wall. Berlin is a world city of culture, start ups, politics, media and science. There are a lot of technology companies in the city. They are important for the city's economy. Many planes and trains travel to and from Berlin because the city is an important place for tourism and business. People. In 2018, Berlin had 3.75 million registered inhabitants in an area of . The city's population density was 4,206 inhabitants per km2. Berlin is the most populous city in Germany and the European Union. The entire Berlin-Brandenburg capital region has a population of more than 6 million in an area of . More than 2.0 million households were counted in the city. Around 60 percent of them were single-person households. There are more than 20 communities with a population of at least 10,000 people in 2019, including German,
The 1930s was the decade that began on January 1, 1930 and ended on December 31, 1939. It is distinct from the decade known as the 194st decade which began on January 1, 1931 and ended on December 31, 1940.
The 1940s (also known as the '40s) was the decade that began on January 1, 1940 and ended on December 31, 1949.
The 1950s began on January 1, 1950 and ended on December 31, 1959. It is distinct from the decade known as the 196th decade which began on January 1, 1951 and ended on December 31, 1960.
Hamburg, or in full Free and Hanseatic City of Hamburg (, Low German: "Friee un Hansestadt Hamborg"), is a city in the north of Germany on the banks of the River Elbe, 18 km away from the North Sea. It is also one of the States of Germany. With a population of about 1.85 million (1850000), it is the biggest German city after Berlin and the sixth largest city of the European Union. The religion is about 37% Protestant, 10% Catholic, 8% Muslim, 38% agnostic, 2% Pagan. Since it was an important member of the Hanseatic League, the city's official name still includes "Hansestadt" (Hanseatic city). Other German cities that do the same today are: Lübeck, Rostock, Wismar, Stralsund, Bremen, Greifswald and Demmin. The membership in this trade alliance has influenced the architecture of the city to a great extent. It has also left some marks in the region around the city. Strategic bombing in World War II devastated the city. In 2017 a consulting company ranked it 17th for best place to live in the world. The area of Hamburg is . It has an oceanic climate ("Cfb" in the Köppen climate classification). Economy. Hamburg's harbour is, by shipments, the second largest harbour in Europe (after Rotterdam) and among the ten largest in the world. It is a very important gate to the countries along the Baltic Sea and Eastern Europe. There are about 120,000 businesses in Hamburg. The company Airbus has an assembly plant for large civil aircraft in Hamburg. 30,000 people are employed in Hamburg's aircraft industries. Only two other places in the world have so many: Seattle in the United States and Toulouse in France. About half of Germany's nationwide newspapers and magazines are made in Hamburg. Germany's most-viewed television news "Tagesschau" is broadcast from Hamburg. Hamburg's red-light district (in Sankt Pauli) is the largest in Europe.
Emphysema is an obstructive disease of the lungs.  It is one of the diseases that make up chronic obstructive pulmonary disease (COPD). This is a set of diseases where the flow of air in the lungs is obstructed. Emphysema is most often caused by smoking but can be caused by other diseases or have no known cause at all. It occurs when the very small air sacs (called the alveoli) at the ends of the airways in the lungs start to break down from many sacs to form much bigger sacs. The alveoli are the areas of the lung where oxygen and carbon dioxide are exchanged into and out of the blood. Emphysema makes it hard for people to blow air out of the lungs because air gets trapped inside the broken alveoli due to the collapse of the walls. The trapped air in the lungs creates the characteristic "barrel chest" of emphysema. There is no cure for emphysema. Treatment includes stopping smoking and taking medicines ('broncho-dilators' and sometimes corticosteroids). Supplemental oxygen is recommended in those with low oxygen levels at rest. It decreases the risk of heart failure and death if used 15 hours per day, and may improve people's ability to exercise. In those with normal or mildly low oxygen levels, oxygen supplementation may improve shortness of breath. There is a risk of fires and little benefit when those on oxygen continue to smoke. Associations. Emphysema is commonly associated with chronic bronchitis. As it is rather difficult to delineate "pure" cases of emphysema or chronic bronchitis they are classed together into chronic obstructive pulmonary disease (COPD).