1.
New York (state)
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New York is a state in the northeastern United States, and is the 27th-most extensive, fourth-most populous, and seventh-most densely populated U. S. state. New York is bordered by New Jersey and Pennsylvania to the south and Connecticut, Massachusetts, and Vermont to the east. With an estimated population of 8.55 million in 2015, New York City is the most populous city in the United States, the New York Metropolitan Area is one of the most populous urban agglomerations in the world. New York City makes up over 40% of the population of New York State, two-thirds of the states population lives in the New York City Metropolitan Area, and nearly 40% lives on Long Island. Both the state and New York City were named for the 17th-century Duke of York, the next four most populous cities in the state are Buffalo, Rochester, Yonkers, and Syracuse, while the state capital is Albany. New York has a diverse geography and these more mountainous regions are bisected by two major river valleys—the north-south Hudson River Valley and the east-west Mohawk River Valley, which forms the core of the Erie Canal. Western New York is considered part of the Great Lakes Region and straddles Lake Ontario, between the two lakes lies Niagara Falls. The central part of the state is dominated by the Finger Lakes, New York had been inhabited by tribes of Algonquian and Iroquoian-speaking Native Americans for several hundred years by the time the earliest Europeans came to New York. The first Europeans to arrive were French colonists and Jesuit missionaries who arrived southward from settlements at Montreal for trade, the British annexed the colony from the Dutch in 1664. The borders of the British colony, the Province of New York, were similar to those of the present-day state, New York is home to the Statue of Liberty, a symbol of the United States and its ideals of freedom, democracy, and opportunity. In the 21st century, New York has emerged as a node of creativity and entrepreneurship, social tolerance. On April 17,1524 Verrazanno entered New York Bay, by way of the now called the Narrows into the northern bay which he named Santa Margherita. Verrazzano described it as a vast coastline with a delta in which every kind of ship could pass and he adds. This vast sheet of water swarmed with native boats and he landed on the tip of Manhattan and possibly on the furthest point of Long Island. Verrazannos stay was interrupted by a storm which pushed him north towards Marthas Vineyard, in 1540 French traders from New France built a chateau on Castle Island, within present-day Albany, due to flooding, it was abandoned the next year. In 1614, the Dutch under the command of Hendrick Corstiaensen, rebuilt the French chateau, Fort Nassau was the first Dutch settlement in North America, and was located along the Hudson River, also within present-day Albany. The small fort served as a trading post and warehouse, located on the Hudson River flood plain, the rudimentary fort was washed away by flooding in 1617, and abandoned for good after Fort Orange was built nearby in 1623. Henry Hudsons 1609 voyage marked the beginning of European involvement with the area, sailing for the Dutch East India Company and looking for a passage to Asia, he entered the Upper New York Bay on September 11 of that year
2.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
3.
Princeton, New Jersey
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As of the 2010 United States Census, the municipalitys population was 28,572, reflecting the former townships population of 16,265, along with the 12,307 in the former borough. Princeton was founded before the American Revolution and is best known as the location of Princeton University, Princeton is roughly equidistant from New York City and Philadelphia. It is close to major highways that serve both cities, and receives major television and radio broadcasts from each. It is also close to Trenton, New Jerseys capital city, the governor of New Jerseys official residence has been in Princeton since 1945, when Morven in the borough became the first Governors mansion. It was later replaced by the larger Drumthwacket, a mansion located in the former Township. Morven became a property of the New Jersey Historical Society. Princeton was ranked 15th of the top 100 towns in the United States to Live, although residents of Princeton traditionally have a strong community-wide identity, the community had been composed of two separate municipalities, a township and a borough. The central borough was completely surrounded by the township, the Borough contained Nassau Street, the main commercial street, most of the University campus, and incorporated most of the urban area until the postwar suburbanization. The Borough and Township had roughly equal populations, the Lenni Lenape Native Americans were the earliest identifiable inhabitants of the Princeton area. Europeans founded their settlement in the part of the 17th century. The first European to find his home in the boundaries of the town was Henry Greenland. He built his house in 1683 along with a tavern, in this drinking hole representatives of West Jersey and East Jersey met to set boundaries for the location of the township. Originally, Princeton was known only as part of nearby Stony Brook, James Leonard first referred to the town as Princetown, when describing the location of his large estate in his diary. The town bore a variety of names subsequently, including, Princetown, Princes Town, although there is no official documentary backing, the town is considered to be named after King William III, Prince William of Orange of the House of Nassau. Another theory suggests that the name came from a large land-owner named Henry Prince, a royal prince seems a more likely eponym for the settlement, as three nearby towns had similar names, Kingston, Queenstown and Princessville. When Richard Stockton, one of the founders of the township, died in 1709 he left his estate to his sons, who helped to expand property, based on the 1880 United States Census, the population of the town comprised 3,209 persons. Local population has expanded from the nineteenth century, according to the 2010 Census, Princeton Borough had 12,307 inhabitants, while Princeton Township had 16,265. Aside from housing the university of the name, the settlement suffered the revolutionary Battle of Princeton on its soil
4.
New Jersey
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New Jersey is a state in the Northeastern and mid-Atlantic regions of the United States. It is bordered on the north and east by New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania, New Jersey is the fourth-smallest state but the 11th-most populous and the most densely populated of the 50 United States. New Jersey lies entirely within the statistical areas of New York City. New Jersey was inhabited by Native Americans for more than 2,800 years, in the early 17th century, the Dutch and the Swedes made the first European settlements. New Jersey was the site of decisive battles during the American Revolutionary War in the 18th century. In the 19th century, factories in cities such as Camden, Paterson, Newark, Trenton, around 180 million years ago, during the Jurassic Period, New Jersey bordered North Africa. The pressure of the collision between North America and Africa gave rise to the Appalachian Mountains, around 18,000 years ago, the Ice Age resulted in glaciers that reached New Jersey. As the glaciers retreated, they left behind Lake Passaic, as well as rivers, swamps. New Jersey was originally settled by Native Americans, with the Lenni-Lenape being dominant at the time of contact, scheyichbi is the Lenape name for the land that is now New Jersey. The Lenape society was divided into clans that were based upon common female ancestors. These clans were organized into three distinct phratries identified by their animal sign, Turtle, Turkey, and Wolf and they first encountered the Dutch in the early 17th century, and their primary relationship with the Europeans was through fur trade. The Dutch became the first Europeans to lay claim to lands in New Jersey, the Dutch colony of New Netherland consisted of parts of modern Middle Atlantic states. Although the European principle of ownership was not recognized by the Lenape. The first to do so was Michiel Pauw who established a patronship called Pavonia in 1630 along the North River which eventually became the Bergen, peter Minuits purchase of lands along the Delaware River established the colony of New Sweden. During the English Civil War, the Channel Island of Jersey remained loyal to the British Crown and it was from the Royal Square in St. Helier that Charles II of England was proclaimed King in 1649, following the execution of his father, Charles I. The North American lands were divided by Charles II, who gave his brother, the Duke of York, the region between New England and Maryland as a proprietary colony. James then granted the land between the Hudson River and the Delaware River to two friends who had remained loyal through the English Civil War, Sir George Carteret and Lord Berkeley of Stratton, the area was named the Province of New Jersey. Since the states inception, New Jersey has been characterized by ethnic, New England Congregationalists settled alongside Scots Presbyterians and Dutch Reformed migrants
5.
Princeton University
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Princeton University is a private Ivy League research university in Princeton, New Jersey, United States. The institution moved to Newark in 1747, then to the current site nine years later, Princeton provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences, and engineering. The university has ties with the Institute for Advanced Study, Princeton Theological Seminary, Princeton has the largest endowment per student in the United States. The university has graduated many notable alumni, two U. S. Presidents,12 U. S. Supreme Court Justices, and numerous living billionaires and foreign heads of state are all counted among Princetons alumni body. New Light Presbyterians founded the College of New Jersey in 1746 in order to train ministers, the college was the educational and religious capital of Scots-Irish America. In 1754, trustees of the College of New Jersey suggested that, in recognition of Governors interest, gov. Jonathan Belcher replied, What a name that would be. In 1756, the moved to Princeton, New Jersey. Its home in Princeton was Nassau Hall, named for the royal House of Orange-Nassau of William III of England, following the untimely deaths of Princetons first five presidents, John Witherspoon became president in 1768 and remained in that office until his death in 1794. During his presidency, Witherspoon shifted the focus from training ministers to preparing a new generation for leadership in the new American nation. To this end, he tightened academic standards and solicited investment in the college, in 1812, the eighth president the College of New Jersey, Ashbel Green, helped establish the Princeton Theological Seminary next door. The plan to extend the theological curriculum met with approval on the part of the authorities at the College of New Jersey. Today, Princeton University and Princeton Theological Seminary maintain separate institutions with ties that include such as cross-registration. Before the construction of Stanhope Hall in 1803, Nassau Hall was the sole building. The cornerstone of the building was laid on September 17,1754, during the summer of 1783, the Continental Congress met in Nassau Hall, making Princeton the countrys capital for four months. The class of 1879 donated twin lion sculptures that flanked the entrance until 1911, Nassau Halls bell rang after the halls construction, however, the fire of 1802 melted it. The bell was then recast and melted again in the fire of 1855, James McCosh took office as the colleges president in 1868 and lifted the institution out of a low period that had been brought about by the American Civil War. McCosh Hall is named in his honor, in 1879, the first thesis for a Doctor of Philosophy Ph. D. was submitted by James F. Williamson, Class of 1877. In 1896, the officially changed its name from the College of New Jersey to Princeton University to honor the town in which it resides
6.
Fellow of the Royal Society
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As of 2016, there are around 1600 living Fellows, Foreign and Honorary Members. Fellowship of the Royal Society has been described by The Guardian newspaper as “the equivalent of a lifetime achievement Oscar” with several institutions celebrating their announcement each year. Up to 60 new Fellows, honorary and foreign members are elected annually usually in May, each candidate is considered on their merits and can be proposed from any sector of the scientific community. Fellows are elected for life on the basis of excellence in science and are entitled to use the post-nominal letters FRS, see Category, Fellows of the Royal Society and Category, Female Fellows of the Royal Society. Every year, Fellows elect up to ten new Foreign Members, like Fellows, Foreign Members are elected for life through peer review on the basis of excellence in science. As of 2016 there are around 165 Foreign Members, who are entitled to use the post-nominal ForMemRS, see Category, Foreign Members of the Royal Society. Honorary Fellows include Bill Bryson, Melvyn Bragg, Robin Saxby, David Sainsbury, Baron Sainsbury of Turville, Honorary Fellows are entitled to use the post nominal letters HonFRS. Others including John Maddox, Patrick Moore and Lisa Jardine were elected as honorary fellows, statute 12 is a legacy mechanism for electing members before official honorary membership existed in 1997. Fellows elected under statute 12 include David Attenborough and John Palmer, prime Ministers of the United Kingdom such as Margaret Thatcher, Neville Chamberlain, H. H. Asquith were elected under statute 12, see Category, Fellows of the Royal Society. The Council of the Royal Society can recommend members of the British Royal Family for election as Royal Fellows of the Royal Society. As of 2016 there are five royal fellows, Charles, Prince of Wales, Anne, Princess Royal, Prince Edward, Duke of Kent, Prince William, Duke of Cambridge and Prince Andrew, Duke of York. Her Majesty the Queen, Elizabeth II is not a Royal Fellow, Prince Philip, Duke of Edinburgh was elected under statute 12, not as a Royal Fellow. The election of new fellows is announced annually in May, after their nomination, each candidate for Fellowship or Foreign Membership is nominated by two Fellows of the Royal Society, who sign a certificate of proposal. Previously, nominations required at least five fellows to support each nomination by the proposer, the certificate of election includes a statement of the principal grounds on which the proposal is being made. There is no limit on the number of nominations each year. In 2015, there were 654 candidates for election as Fellows and 106 candidates for Foreign Membership. The final list of up to 52 Fellowship candidates and up to 10 Foreign Membership candidates is confirmed by the Council in April, a candidate is elected if he or she secures two-thirds of votes of those Fellows present and voting. A further maximum of six can be ‘Honorary’, ‘General’ or ‘Royal’ Fellows, nominations for Fellowship are peer reviewed by sectional committees, each with fifteen members and a chair
7.
Astronomy
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Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets, while the phenomena include supernovae explosions, gamma ray bursts, more generally, all astronomical phenomena that originate outside Earths atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole, Astronomy is the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, during the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the results and observations being used to confirm theoretical results. Astronomy is one of the few sciences where amateurs can play an active role, especially in the discovery. Amateur astronomers have made and contributed to many important astronomical discoveries, Astronomy means law of the stars. Astronomy should not be confused with astrology, the system which claims that human affairs are correlated with the positions of celestial objects. Although the two share a common origin, they are now entirely distinct. Generally, either the term astronomy or astrophysics may be used to refer to this subject, however, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics. Few fields, such as astrometry, are purely astronomy rather than also astrophysics, some titles of the leading scientific journals in this field includeThe Astronomical Journal, The Astrophysical Journal and Astronomy and Astrophysics. In early times, astronomy only comprised the observation and predictions of the motions of objects visible to the naked eye, in some locations, early cultures assembled massive artifacts that possibly had some astronomical purpose. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye, most of early astronomy actually consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon, the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the model of the Universe, or the Ptolemaic system. The Babylonians discovered that lunar eclipses recurred in a cycle known as a saros
8.
Harlow Shapley
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Harlow Shapley was an American astronomer. He used RR Lyrae stars to correctly estimate the size of the Milky Way Galaxy, in 1953 he proposed his liquid water belt theory, now known as the concept of a habitable zone. Shapley was born on a farm in Nashville, Missouri, to Willis and Sarah Shapley, after studying at home and covering crime stories as a newspaper reporter, Shapley returned to complete a six-year high school program in only two years, graduating as class valedictorian. In 1907, Shapley went to journalism at the University of Missouri. When he learned that the opening of the School of Journalism had been postponed for a year, rejecting Archaeology, which Harlow later explained he couldnt pronounce, he chose the next subject, Astronomy. He was instrumental in moving away from the idea that Cepheids were spectroscopic binaries. He realized the Milky Way Galaxy was far larger than previously believed, and this discovery by Shapley is a part of the Copernican principle, according to which the Earth is not at the center of our Solar System, our galaxy, or our Universe. Shapley participated in the Great Debate with Heber D. Curtis on the nature of nebulae and galaxies, the debate took place on April 26,1920, in the hall of the United States National Academy of Sciences in Washington D. C. This issue and debate are the start of extragalactic astronomy, while the detailed arguments and data, often with ambiguities, however, Shapleys actual talk and argument given during the Great Debate was completely different from the published paper. Historian Michael Hoskin says His decision was to treat the National Academy of Sciences to an address so elementary that much of it was necessarily uncontroversial. With Shapleys motivation being only to impress a delegation from Harvard who were interviewing him for an offer as the next Director of Harvard College Observatory. With the default by Shapley, Curtis won the debate, the astronomical issues were soon resolved in favor of Curtis position when Edwin Hubble discovered Cepheid variable stars in the Andromeda Galaxy. At the time of the debate, Shapley was working at the Mount Wilson Observatory, after the debate, however, he was hired to replace the recently deceased Edward Charles Pickering as director of the Harvard College Observatory. He is also known to have incorrectly opposed Edwin Hubbles observations that there are additional galaxies in the other than the Milky Way. Shapley fiercely critiqued Hubble and regarded his work as junk science, however, after he received a letter from Hubble showing Hubbles observed light curve of V1, he withdrew his criticism. He reportedly told a colleague, Here is the letter that destroyed my universe and he also encouraged Hubble to write a paper for a joint meeting of the American Astronomical Society and American Association for the Advancement of Science. Hubbles findings went on to reshape fundamentally the scientific view of the universe and he served as director of the HCO from 1921 to 1952. During this time, he hired Cecilia Payne, who, in 1925, became the first person to earn a doctorate at Radcliffe College in the field of astronomy and he wrote many books on astronomy and the sciences
9.
Astronomer
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An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside of the scope of Earth. They look at stars, planets, moons, comets and galaxies, as well as other celestial objects — either in observational astronomy. Examples of topics or fields astronomers work on include, planetary science, solar astronomy, there are also related but distinct subjects like physical cosmology which studies the Universe as a whole. Astronomers usually fit into two types, Observational astronomers make direct observations of planets, stars and galaxies, and analyze the data, theoretical astronomers create and investigate models of things that cannot be observed. They use this data to create models or simulations to theorize how different celestial bodies work, there are further subcategories inside these two main branches of astronomy such as planetary astronomy, galactic astronomy or physical cosmology. Today, that distinction has disappeared and the terms astronomer. Professional astronomers are highly educated individuals who typically have a Ph. D. in physics or astronomy and are employed by research institutions or universities. They spend the majority of their time working on research, although quite often have other duties such as teaching, building instruments. The number of astronomers in the United States is actually quite small. The American Astronomical Society, which is the organization of professional astronomers in North America, has approximately 7,000 members. This number includes scientists from other such as physics, geology. The International Astronomical Union comprises almost 10,145 members from 70 different countries who are involved in research at the Ph. D. level. Before CCDs, photographic plates were a method of observation. Modern astronomers spend relatively little time at telescopes usually just a few weeks per year, analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes, most universities also have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field. Those who become astronomers usually have a background in maths, sciences. Taking courses that teach how to research, write and present papers are also invaluable, in college/university most astronomers get a Ph. D. in astronomy or physics. Keeping in mind how few there are it is understood that graduate schools in this field are very competitive
10.
George Darwin
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Sir George Howard Darwin KCB FRS FRSE was an English barrister, eugenicist, astronomer, and mathematician. George Darwin was born at Down House, Kent, the son and fifth child of Charles Darwin. He graduated as second wrangler in 1868, when he was placed second for the Smiths Prize and was appointed to a college fellowship. He earned his M. A. in 1871 and he was admitted to the bar in 1872, but returned to science. He was elected a Fellow of the Royal Society in June 1879 and won their Royal Medal in 1884 and he delivered their Bakerian Lecture in 1891 on the subject of tidal prediction. In 1883 Darwin became Plumian Professor of Astronomy and Experimental Philosophy at the University of Cambridge and he studied tidal forces involving the Sun, Moon, and Earth, and formulated the fission theory of Moon formation. Darwin was a Fellow of the Royal Astronomical Society and won the Gold Medal of the RAS in 1892, from 1899–1901 he served as President of the RAS. The RAS founded a prize lectureship in 1984 and named it the George Darwin Lectureship in Darwins honour and he was an invited speaker in the International Congress of Mathematicians 1908, Rome on the topic of Mechanics, Physical Mathematics, Astronomy. As President of the Cambridge Philosophical Society, he gave the Introductory Address to the Congress in 1912 on the character of pure. George and Maud Darwin bought Newnham Grange, Cambridge in 1885, the Darwins extensively remodelled the house. Since 1962 the Grange has been part of Darwin College, Cambridge, Darwin married Martha du Puy, the daughter of Charles du Puy of Philadelphia, in 1884, his wife was a member of the Ladies Dining Society in Cambridge, with 11 other members. She died on 6 February 1947 and they had three sons and two daughters, Gwen Raverat, artist. Sir Charles Galton Darwin, physicist and applied mathematics, margaret Elizabeth Darwin, married Sir Geoffrey Keynes. William Robert Darwin Leonard Darwin Tides, Scientific papers, Figures of equilibrium of rotating liquid and geophysical investigations. Scientific papers, Periodic orbits and miscellaneous papers, Scientific papers Supplementary volume, containing biographical memoirs by Sir Francis Darwin and Professor E. W. Brown, lectures on Hills lunar theory, etc. The Scientific Papers of Sir George Darwin, Cambridge University Press On Beneficial Restrictions to Liberty of Marriage, The Contemporary Review, Vol. XXII, June/November 1873. Commodities Versus Labour, The Contemporary Review, Vol. XXII, the Birth of a Satellite Harpers Monthly Magazine, December 1903, pages 124 to 130. George Howard Darwin at the Mathematics Genealogy Project The Genesis of Double Stars – by George Darwin, from A. C. Sewards Darwin, archival material relating to George Darwin
11.
Stellar evolution
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Stellar evolution is the process by which a star changes over the course of time. The table shows the lifetimes of stars as a function of their masses, all stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star, later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Once a star like the Sun has exhausted its fuel, its core collapses into a dense white dwarf. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into a dense neutron star or black hole. Stellar evolution is not studied by observing the life of a star, as most stellar changes occur too slowly to be detected. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, in June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z =6.60. Stellar evolution starts with the collapse of a giant molecular cloud. Typical giant molecular clouds are roughly 100 light-years across and contain up to 6,000,000 solar masses, as it collapses, a giant molecular cloud breaks into smaller and smaller pieces. In each of these fragments, the collapsing gas releases gravitational potential energy as heat, as its temperature and pressure increase, a fragment condenses into a rotating sphere of superhot gas known as a protostar. A protostar continues to grow by accretion of gas and dust from the molecular cloud, further development is determined by its mass. Protostars are encompassed in dust, and are more readily visible at infrared wavelengths. Observations from the Wide-field Infrared Survey Explorer have been important for unveiling numerous Galactic protostars. Protostars with masses less than roughly 0.08 M☉ never reach high enough for nuclear fusion of hydrogen to begin. These are known as brown dwarfs, the International Astronomical Union defines brown dwarfs as stars massive enough to fuse deuterium at some point in their lives. Objects smaller than 13 MJ are classified as sub-brown dwarfs, both types, deuterium-burning and not, shine dimly and die away slowly, cooling gradually over hundreds of millions of years
