1.
Buffalo, New York
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Buffalo is a city in western New York state and the county seat of Erie County, on the eastern shores of Lake Erie at the head of the Niagara River. As of 2014, Buffalo is New York states 2nd-most populous city after New York City, the metropolitan area has a population of 1.13 million. After an economic downturn in the half of the 20th century, Buffalos economy has transitioned to sectors that include financial services, technology, biomedical engineering. Residents of Buffalo are called Buffalonians, the citys nicknames include The Queen City, The Nickel City and The City of Good Neighbors. The city of Buffalo received its name from a creek called Buffalo Creek. British military engineer Captain John Montresor made reference to Buffalo Creek in his journal of 1764, there are several theories regarding how Buffalo Creek received its name. In 1804, as principal agent opening the area for the Holland Land Company, Joseph Ellicott, designed a radial street and grid system that branches out from downtown like bicycle spokes similar to the street system he used in the nations capital. Although Ellicott named the settlement New Amsterdam, the name did not catch on, during the War of 1812, on December 30,1813, Buffalo was burned by British forces. The George Coit House 1818 and Samuel Schenck House 1823 are currently the oldest houses within the limits of the City of Buffalo, on October 26,1825, the Erie Canal was completed with Buffalo a port-of-call for settlers heading westward. At the time, the population was about 2,400, the Erie Canal brought about a surge in population and commerce, which led Buffalo to incorporate as a city in 1832. In 1845, construction began on the Macedonia Baptist Church, an important meeting place for the abolitionist movement, Buffalo was a terminus point of the Underground Railroad with many fugitive slaves crossing the Niagara River to Fort Erie, Ontario in search of freedom. During the 1840s, Buffalos port continued to develop, both passenger and commercial traffic expanded with some 93,000 passengers heading west from the port of Buffalo. Grain and commercial goods shipments led to repeated expansion of the harbor, in 1843, the worlds first steam-powered grain elevator was constructed by local merchant Joseph Dart and engineer Robert Dunbar. Darts Elevator enabled faster unloading of lake freighters along with the transshipment of grain in bulk from barges, canal boats, by 1850, the citys population was 81,000. At the dawn of the 20th century, local mills were among the first to benefit from hydroelectric power generated by the Niagara River, the city got the nickname City of Light at this time due to the widespread electric lighting. It was also part of the revolution, hosting the brass era car builders Pierce Arrow. President William McKinley was shot and mortally wounded by an anarchist at the Pan-American Exposition in Buffalo on September 6,1901, McKinley died in the city eight days later and Theodore Roosevelt was sworn in at the Wilcox Mansion as the 26th President of the United States. The Great Depression of 1929–39 saw severe unemployment, especially working class men
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.
University of Southern California
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The University of Southern California is a private research university founded in 1880 with its main campus in Los Angeles, California. As Californias oldest private university, USC has historically educated a large number of the regions business leaders. In recent decades, the university has also leveraged its location in Los Angeles to establish relationships with research and cultural institutions throughout Asia, an engine for economic activity, USC contributes $8 billion annually to the economy of the Los Angeles metropolitan area and California. For the 2014–15 academic year, there were 18,740 students enrolled in undergraduate programs. USC also has 23,729 graduate and professional students in a number of different programs, including business, law, engineering, social work, and medicine. The university is one of the top fundraising institutions in the world, consistently ranking among the top 3 in external contributions, multiple academic rankings list the University of Southern California as being among the top 25 universities in the United States. With an acceptance rate of 16 percent, USC is also among the most selective academic institutions in the nation. USC maintains a tradition of innovation and entrepreneurship, with alumni having founded companies such as Lucasfilm, Myspace, Salesforce. com, Intuit, Qualcomm, Box, Tinder. As of 2014, the university has produced the fourth largest number of billionaire alumni out of all institutions in the world. USC is home to the world’s most powerful computer, which is presently housed in a super-cooled. The only other commercially available quantum computing system is operated jointly by NASA, USC was also one of the earliest nodes on ARPANET and is the birthplace of the Domain Name System. Other technologies invented at USC include DNA computing, dynamic programming, image compression, VoIP, USC sponsors a variety of intercollegiate sports and competes in the National Collegiate Athletic Association as a member of the Pac-12 Conference. Members of the teams, the Trojans, have won 102 NCAA team championships, ranking them third in the nation. Trojan athletes have won 288 medals at the Olympic games, more than any university in the United States. If USC were a country, its athletes would have received the 12th-most Olympic gold medals in history. In 1969, it joined the Association of American Universities, the University of Southern California was founded following the efforts of Judge Robert M. Hellman. The three donated 308 lots of land to establish the campus and provided the seed money for the construction of the first buildings. Originally operated in affiliation with the Methodist Church, the school mandated from the start that no student would be denied admission because of race, the university is no longer affiliated with any church, having severed formal ties in 1952
4.
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
5.
California Institute of Technology
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The California Institute of Technology is a private doctorate-granting university located in Pasadena, California, United States. The vocational and preparatory schools were disbanded and spun off in 1910, the university is one among a small group of Institutes of Technology in the United States which is primarily devoted to the instruction of technical arts and applied sciences. Caltech has six divisions with strong emphasis on science and engineering, managing $332 million in 2011 in sponsored research. Its 124-acre primary campus is located approximately 11 mi northeast of downtown Los Angeles, first-year students are required to live on campus, and 95% of undergraduates remain in the on-campus House System at Caltech. Although Caltech has a tradition of practical jokes and pranks. The Caltech Beavers compete in 13 intercollegiate sports in the NCAA Division IIIs Southern California Intercollegiate Athletic Conference, Caltech is frequently cited as one of the worlds best universities. There are 112 faculty members who have elected to the United States National Academies. In addition, numerous faculty members are associated with the Howard Hughes Medical Institute as well as NASA, according to a 2015 Pomona College study, Caltech ranked number one in the U. S. for the percentage of its graduates who go on to earn a PhD. Caltech started as a school founded in Pasadena in 1891 by local businessman and politician Amos G. Throop. The school was known successively as Throop University, Throop Polytechnic Institute, the vocational school was disbanded and the preparatory program was split off to form an independent Polytechnic School in 1907. At a time when research in the United States was still in its infancy, George Ellery Hale. He joined Throops board of trustees in 1907, and soon began developing it and he engineered the appointment of James A. B. Scherer, a literary scholar untutored in science but a capable administrator and fund raiser, scherer persuaded retired businessman and trustee Charles W. Gates to donate $25,000 in seed money to build Gates Laboratory, the first science building on campus. In 1910, Throop moved to its current site, arther Fleming donated the land for the permanent campus site. The promise of Throop attracted physical chemist Arthur Amos Noyes from MIT to develop the institution and assist in establishing it as a center for science, with the onset of World War I, Hale organized the National Research Council to coordinate and support scientific work on military problems. This institution, with its able investigators and excellent research laboratories, through the National Research Council, Hale simultaneously lobbied for science to play a larger role in national affairs, and for Throop to play a national role in science. During the course of the war, Hale, Noyes and Millikan worked together in Washington on the NRC, subsequently, they continued their partnership in developing Caltech. Under the leadership of Hale, Noyes and Millikan, Caltech grew to prominence in the 1920s
6.
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
7.
Solar System
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The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets, with the remainder being significantly smaller objects, such as dwarf planets, of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury. The Solar System formed 4.6 billion years ago from the collapse of a giant interstellar molecular cloud. The vast majority of the mass is in the Sun. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being composed of rock. The four outer planets are giant planets, being more massive than the terrestrials. All planets have almost circular orbits that lie within a flat disc called the ecliptic. The Solar System also contains smaller objects, the asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptunes orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity. Such objects are categorized as dwarf planets, identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris. In addition to two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds. Six of the planets, at least four of the dwarf planets, each of the outer planets is encircled by planetary rings of dust and other small objects. The solar wind, a stream of charged particles flowing outwards from the Sun, the heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium, it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, the Solar System is located in the Orion Arm,26,000 light-years from the center of the Milky Way. For most of history, humanity did not recognize or understand the concept of the Solar System, the invention of the telescope led to the discovery of further planets and moons. The principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99. 86% of the known mass. The Suns four largest orbiting bodies, the giant planets, account for 99% of the mass, with Jupiter. The remaining objects of the Solar System together comprise less than 0. 002% of the Solar Systems total mass, most large objects in orbit around the Sun lie near the plane of Earths orbit, known as the ecliptic
8.
Mount Wilson Observatory
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The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 1, 740-metre peak in the San Gabriel Mountains near Pasadena, the observatory was conceived and founded by George Ellery Hale, who had previously built the 1 meter telescope at the Yerkes Observatory, then the worlds largest telescope. The Mount Wilson Solar Observatory was first funded by the Carnegie Institution of Washington in 1904, among the conditions of the lease was that it allow public access. There are three solar telescopes at Mount Wilson Observatory, today, just one of these telescopes, the 60 foot Solar Tower, is still used for solar research. The Snow Solar Telescope was the first telescope installed at the fledgling Mount Wilson Solar Observatory and it was the worlds first permanently mounted solar telescope. Solar telescopes had previously been portable so they could be taken to solar eclipses around the world, the telescope was donated to Yerkes Observatory by Helen Snow of Chicago. George Ellery Hale, then director of Yerkes, had the telescope brought to Mount Wilson to put it into service as a scientific instrument. Stellar research soon followed as the brightest stars could have their spectra recorded with very long exposures on glass plates, today the Snow solar telescope is mostly used by undergraduate students who get hands on training in solar physics and spectroscopy. It was also used publicly for the May 9,2016 transit of Mercury across the face of the sun, the 60-foot Solar Tower soon built on the work started at the Snow telescope. At its completion in 1908, the tower design of the 60 foot focal length solar telescope allowed much higher resolution of the solar image. The higher resolution came from situating the optics higher above the ground, on June 25,1908, Hale would record Zeeman splitting in the spectrum of a sunspot, showing for the first time that magnetic fields existed somewhere besides the earth. A later discovery was of the polarity in sunspots of the new solar cycle of 1912. The success of the 60 foot Tower prompted Hale to pursue yet another, taller tower telescope, in the 1960s, Robert Leighton discovered the sun had a 5-minute oscillation and the field of heliosiesmology was born. The 60 foot Tower is operated by the Department of Physics, the 150-foot focal length solar tower expanded on the solar tower design with its tower-in-a-tower design. An inner tower supports the optics above, while an outer tower and this design allowed complete isolation of the optics from the effect of wind swaying the tower. Two mirrors feed sunlight to a 12-inch lens which focuses light down at the ground floor and it was first completed in 1910, but unsatisfactory optics caused a two-year delay before a suitable doublet lens was installed. Research included solar rotation, sunspot polarities, daily sunspot drawings, the solar telescope would be the worlds largest for 50 years until the McMath-Pierce Solar telescope was completed at Kitt Peak in Arizona in 1962. In 1985, UCLA took over operation of the tower from the Carnegie Observatories after it was decided to stop funding the observatory
9.
Jupiter
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Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, Jupiter and Saturn are gas giants, the other two giant planets, Uranus and Neptune are ice giants. Jupiter has been known to astronomers since antiquity, the Romans named it after their god Jupiter. Jupiter is primarily composed of hydrogen with a quarter of its mass being helium and it may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rotation, the planets shape is that of an oblate spheroid. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence, a prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere, Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a greater than that of the planet Mercury. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, the latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4,2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa, Earth and its neighbor planets may have formed from fragments of planets after collisions with Jupiter destroyed those super-Earths near the Sun. Astronomers have discovered nearly 500 planetary systems with multiple planets, Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter is composed primarily of gaseous and liquid matter and it is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km at its equator, the average density of Jupiter,1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiters upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, a helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiters atmosphere is approximately 75% hydrogen and 24% helium by mass, the atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, the outermost layer of the atmosphere contains crystals of frozen ammonia. The interior contains denser materials - by mass it is roughly 71% hydrogen, 24% helium, through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found
10.
Asteroid
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Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids and these terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet. As minor planets in the outer Solar System were discovered and found to have volatile-based surfaces that resemble those of comets, in this article, the term asteroid refers to the minor planets of the inner Solar System including those co-orbital with Jupiter. There are millions of asteroids, many thought to be the remnants of planetesimals. The large majority of known asteroids orbit in the belt between the orbits of Mars and Jupiter, or are co-orbital with Jupiter. However, other orbital families exist with significant populations, including the near-Earth objects, individual asteroids are classified by their characteristic spectra, with the majority falling into three main groups, C-type, M-type, and S-type. These were named after and are identified with carbon-rich, metallic. The size of asteroids varies greatly, some reaching as much as 1000 km across, asteroids are differentiated from comets and meteoroids. In the case of comets, the difference is one of composition, while asteroids are composed of mineral and rock, comets are composed of dust. In addition, asteroids formed closer to the sun, preventing the development of the aforementioned cometary ice, the difference between asteroids and meteoroids is mainly one of size, meteoroids have a diameter of less than one meter, whereas asteroids have a diameter of greater than one meter. Finally, meteoroids can be composed of either cometary or asteroidal materials, only one asteroid,4 Vesta, which has a relatively reflective surface, is normally visible to the naked eye, and this only in very dark skies when it is favorably positioned. Rarely, small asteroids passing close to Earth may be visible to the eye for a short time. As of March 2016, the Minor Planet Center had data on more than 1.3 million objects in the inner and outer Solar System, the United Nations declared June 30 as International Asteroid Day to educate the public about asteroids. The date of International Asteroid Day commemorates the anniversary of the Tunguska asteroid impact over Siberia, the first asteroid to be discovered, Ceres, was found in 1801 by Giuseppe Piazzi, and was originally considered to be a new planet. In the early half of the nineteenth century, the terms asteroid. Asteroid discovery methods have improved over the past two centuries. This task required that hand-drawn sky charts be prepared for all stars in the band down to an agreed-upon limit of faintness. On subsequent nights, the sky would be charted again and any moving object would, hopefully, the expected motion of the missing planet was about 30 seconds of arc per hour, readily discernible by observers
11.
Comet
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A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to evolve gasses, a process called outgassing. This produces an atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of collections of ice, dust. The coma may be up to 15 times the Earths diameter, if sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° across the sky. Comets have been observed and recorded since ancient times by many cultures, Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star. Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars, hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition, Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma and the tail, however, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System, the discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. As of November 2014 there are 5,253 known comets, however, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System is estimated to be one trillion. Roughly one comet per year is visible to the eye, though many of those are faint. Particularly bright examples are called Great Comets, the word comet derives from the Old English cometa from the Latin comēta or comētēs. That, in turn, is a latinisation of the Greek κομήτης, Κομήτης was derived from κομᾶν, which was itself derived from κόμη and was used to mean the tail of a comet. The astronomical symbol for comets is ☄, consisting of a disc with three hairlike extensions. The solid, core structure of a comet is known as the nucleus, cometary nuclei are composed of an amalgamation of rock, dust, water ice, and frozen gases such as carbon dioxide, carbon monoxide, methane, and ammonia. As such, they are described as dirty snowballs after Fred Whipples model
12.
Type Ia supernova
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A type Ia supernova is a type of supernova that occurs in binary systems in which one of the stars is a white dwarf. The other star can be anything from a giant star to a smaller white dwarf. Physically, carbon–oxygen white dwarfs with a low rate of rotation are limited to below 1.44 solar masses, beyond this, they re-ignite and in some cases trigger a supernova explosion. If a white dwarf accretes mass from a binary companion. If the white dwarf merges with another white dwarf, it will exceed the limit and begin to collapse. This type Ia category of supernovae produces consistent peak luminosity because of the mass of white dwarfs that explode via the accretion mechanism. In May 2015, NASA reported that the Kepler space observatory observed KSN 2011b, details of the pre-nova moments may help scientists better judge the quality of Type Ia supernovae as standard candles, which is an important link in the argument for dark energy. The Type Ia supernova is a sub-category in the Minkowski-Zwicky supernova classification scheme, there are several means by which a supernova of this type can form, but they share a common underlying mechanism. The current view among astronomers who model Type Ia supernova explosions, however, is that limit is never actually attained. At some point in this phase, a deflagration flame front is born. The details of the ignition are still unknown, including the location, oxygen fusion is initiated shortly thereafter, but this fuel is not consumed as completely as carbon. Once fusion has begun, the temperature of the white dwarf starts to rise, a main sequence star supported by thermal pressure would expand and cool which automatically counterbalances an increase in thermal energy. However, degeneracy pressure is independent of temperature, the dwarf is unable to regulate the fusion process in the manner of normal stars. The flame accelerates dramatically, in due to the Rayleigh–Taylor instability. It is still a matter of debate whether this flame transforms into a supersonic detonation from a subsonic deflagration. The star explodes violently and releases a wave in which matter is typically ejected at speeds on the order of 5, 000–20000 km/s. The energy released in the explosion causes an extreme increase in luminosity. The typical visual absolute magnitude of Type Ia supernovae is Mv = −19.3, the theory of this type of supernovae is similar to that of novae, in which a white dwarf accretes matter more slowly and does not approach the Chandrasekhar limit
