An astronomical object , celestial object , stellar object or heavenly body is a naturally occurring physical entity , association, or structure that exists within the observable universe . In astronomy , the terms object and body are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial object is a complex, less cohesively bound structure, which may consist of multiple bodies or even other objects with substructures.
42-616: Manali Kallat Vainu Bappu (10 August 1927 – 19 August 1982) was an Indian astronomer and president of the International Astronomical Union . Bappu helped to establish several astronomical institutions in India, including the Vainu Bappu Observatory which is named after him, and he also contributed to the establishment of the modern Indian Institute of Astrophysics . In 1957, he discovered
84-427: A supermassive black hole , which may result in an active galactic nucleus . Galaxies can also have satellites in the form of dwarf galaxies and globular clusters . The constituents of a galaxy are formed out of gaseous matter that assembles through gravitational self-attraction in a hierarchical manner. At this level, the resulting fundamental components are the stars, which are typically assembled in clusters from
126-458: A variable star . An example of this is the instability strip , a region of the H-R diagram that includes Delta Scuti , RR Lyrae and Cepheid variables . The evolving star may eject some portion of its atmosphere to form a nebula, either steadily to form a planetary nebula or in a supernova explosion that leaves a remnant . Depending on the initial mass of the star and the presence or absence of
168-542: A companion, a star may spend the last part of its life as a compact object ; either a white dwarf , neutron star , or black hole . The IAU definitions of planet and dwarf planet require that a Sun-orbiting astronomical body has undergone the rounding process to reach a roughly spherical shape, an achievement known as hydrostatic equilibrium . The same spheroidal shape can be seen on smaller rocky planets like Mars to gas giants like Jupiter . Any natural Sun-orbiting body that has not reached hydrostatic equilibrium
210-632: A research observatory led to the founding of the optical observatory of Kavalur and its large telescope. The Vainu Bappu Observatory is one of the main observatories of the Indian Institute of Astrophysics , also initiated in its modern avatar by Bappu in 1971. Later, a number of discoveries were made from the Vainu Bappu Observatory. International Astronomical Union The International Astronomical Union ( IAU ; French : Union astronomique internationale , UAI )
252-551: A study assessing the feasibility of the Communicating Astronomy with the Public Journal ( CAP Journal ). Astronomical object Examples of astronomical objects include planetary systems , star clusters , nebulae , and galaxies , while asteroids , moons , planets , and stars are astronomical bodies. A comet may be identified as both a body and an object: It is a body when referring to
294-426: A web that spans the observable universe. Galaxies have a variety of morphologies , with irregular , elliptical and disk-like shapes, depending on their formation and evolutionary histories, including interaction with other galaxies, which may lead to a merger . Disc galaxies encompass lenticular and spiral galaxies with features, such as spiral arms and a distinct halo . At the core, most galaxies have
336-585: Is Teaching Astronomy for Development (TAD) program in countries where there is currently very little astronomical education. Another program is named the Galileo Teacher Training Program (GTTP), is a project of the International Year of Astronomy 2009, among which Hands-On Universe that will concentrate more resources on education activities for children and schools designed to advance sustainable global development. GTTP
378-692: Is a member of the International Science Council , which is composed of international scholarly and scientific institutions and national academies of sciences . The International Astronomical Union is an international association of professional astronomers , at the PhD level and beyond, active in professional research and education in astronomy . Among other activities, it acts as the recognized authority for assigning designations and names to celestial bodies ( stars , planets , asteroids , etc.) and any surface features on them. The IAU
420-534: Is a member of the International Science Council . Its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU maintains friendly relations with organizations that include amateur astronomers in their membership. The IAU has its head office on the second floor of the Institut d'Astrophysique de Paris in the 14th arrondissement of Paris . This organisation has many working groups. For example,
462-526: Is affiliated with the International Council of Scientific Unions (ICSU), a non-governmental organization representing a global membership that includes both national scientific bodies and international scientific unions. They often encourage countries to become members of the IAU. The Commission further seeks to development, information or improvement of astronomical education. Part of Commission 46,
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#1732793223046504-802: Is also concerned with the effective use and transfer of astronomy education tools and resources into classroom science curricula. A strategic plan for the period 2010–2020 has been published. In 2004 the IAU contracted with the Cambridge University Press to publish the Proceedings of the International Astronomical Union . In 2007, the Communicating Astronomy with the Public Journal Working Group prepared
546-797: Is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded on 28 July 1919 in Brussels , Belgium and is based in Paris , France . The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of May 2024,
588-538: Is classified by the IAU as a small Solar System body (SSSB). These come in many non-spherical shapes which are lumpy masses accreted haphazardly by in-falling dust and rock; not enough mass falls in to generate the heat needed to complete the rounding. Some SSSBs are just collections of relatively small rocks that are weakly held next to each other by gravity but are not actually fused into a single big bedrock . Some larger SSSBs are nearly round but have not reached hydrostatic equilibrium. The small Solar System body 4 Vesta
630-586: Is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority . An equality of votes is resolved by the vote of the President of the Union. Since 1922, the IAU General Assembly meets every three years, except for the period between 1938 and 1948, due to World War II . After a Polish request in 1967, and by a controversial decision of the then President of
672-517: The Andromeda nebula as a different galaxy, along with many others far from the Milky Way. The universe can be viewed as having a hierarchical structure. At the largest scales, the fundamental component of assembly is the galaxy . Galaxies are organized into groups and clusters , often within larger superclusters , that are strung along great filaments between nearly empty voids , forming
714-867: The International Central Bureau of Astronomical Telegrams initially seated in Copenhagen , Denmark. The seven initial member states were Belgium, Canada, France, Great Britain, Greece, Japan, and the United States, soon to be followed by Italy and Mexico. The first executive committee consisted of Benjamin Baillaud (President, France), Alfred Fowler (General Secretary, UK), and four vice presidents: William Campbell (US), Frank Dyson (UK), Georges Lecointe (Belgium), and Annibale Riccò (Italy). Thirty-two Commissions (referred to initially as Standing Committees) were appointed at
756-663: The Moon , and sunspots on the Sun. Astronomer Edmond Halley was able to successfully predict the return of Halley's Comet , which now bears his name, in 1758. In 1781, Sir William Herschel discovered the new planet Uranus , being the first discovered planet not visible by the naked eye. In the 19th and 20th century, new technologies and scientific innovations allowed scientists to greatly expand their understanding of astronomy and astronomical objects. Larger telescopes and observatories began to be built and scientists began to print images of
798-797: The Royal Astronomical Society of New Zealand , the Royal Swedish Academy of Sciences , the Russian Academy of Sciences , and the Science Council of Japan , among many others. The sovereign body of the IAU is its General Assembly , which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union (and amendments proposed thereto) and elects various committees. The right to vote on matters brought before
840-639: The Scientific Revolution , in 1543, Nicolaus Copernicus's heliocentric model was published. This model described the Earth , along with all of the other planets as being astronomical bodies which orbited the Sun located in the center of the Solar System . Johannes Kepler discovered Kepler's laws of planetary motion , which are properties of the orbits that the astronomical bodies shared; this
882-518: The Wilson–Bappu effect jointly with American astronomer Olin Chaddock Wilson . On 2 July 1949, when Bappu was taking pictures of the night sky, he spotted a bright moving object which he had rightfully understood to be a comet . When he turned to his professor, Bart Bok , and colleague Gordon Newkirk, they confirmed the discovery. They calculated the orbit of the comet which revealed that
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#1732793223046924-560: The Wilson–Bappu effect . The effect as described by L.V. Kuhi is: 'The width of the Ca II emission in normal, nonvariable, G, K, and M stars is correlated with the visual absolute magnitude in the sense that the brighter the star the wider the emission.' The paper opened up the field of stellar chromospheres for research. On his return to India, Bappu was appointed to head a team of astronomers to build an observatory at Nainital . His efforts of building an indigenous large optical telescope and
966-491: The protoplanetary disks that surround newly formed stars. The various distinctive types of stars are shown by the Hertzsprung–Russell diagram (H–R diagram)—a plot of absolute stellar luminosity versus surface temperature. Each star follows an evolutionary track across this diagram. If this track takes the star through a region containing an intrinsic variable type, then its physical properties can cause it to become
1008-466: The Assembly varies according to the type of business under discussion. The Statutes consider such business to be divided into two categories: On budget matters (which fall into the second category), votes are weighted according to the relative subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members to be valid. An absolute majority
1050-582: The Brussels meeting and focused on topics ranging from relativity to minor planets. The reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, 2–10 May 1922. By the end of the first General Assembly, ten additional nations (Australia, Brazil, Czechoslovakia, Denmark, the Netherlands, Norway, Poland, Romania, South Africa, and Spain) had joined
1092-662: The IAU, an Extraordinary IAU General Assembly was held in September 1973 in Warsaw , Poland, to commemorate the 500th anniversary of the birth of Nicolaus Copernicus , soon after the regular 1973 GA had been held in Sydney. Sources. Commission 46 is a Committee of the Executive Committee of the IAU, playing a special role in the discussion of astronomy development with governments and scientific academies. The IAU
1134-871: The IAU, and is a "clearinghouse" for all non-planetary or non-moon bodies in the Solar System. The IAU was founded on 28 July 1919, at the Constitutive Assembly of the International Research Council (now the International Science Council ) held in Brussels , Belgium. Two subsidiaries of the IAU were also created at this assembly: the International Time Commission seated at the International Time Bureau in Paris, France, and
1176-1004: The IAU. National members include the Australian Academy of Science , the Chinese Astronomical Society, the French Academy of Sciences , the Indian National Science Academy , the National Academies (United States) , the National Research Foundation of South Africa , the National Scientific and Technical Research Council (Argentina), the Council of German Observatories, the Royal Astronomical Society (United Kingdom),
1218-483: The Moon and other celestial bodies on photographic plates. New wavelengths of light unseen by the human eye were discovered, and new telescopes were made that made it possible to see astronomical objects in other wavelengths of light. Joseph von Fraunhofer and Angelo Secchi pioneered the field of spectroscopy , which allowed them to observe the composition of stars and nebulae, and many astronomers were able to determine
1260-630: The Union had 85 national members and 12,734 individual members, spanning 90 countries and territories. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy and includes various scientific meetings. The Union is best known for being the leading authority in assigning official names and designations to astronomical objects , and for setting uniform definitions for astronomical principles. It also coordinates with national and international partners, such as UNESCO , to fulfill its mission. The IAU
1302-689: The Union held the NameExoWorlds contests. Starting in 2024, the Union, in partnership with the United Nations , is poised to play a critical role in developing the legislation and framework for lunar industrialization . As of 1 August 2019, the IAU has a total of 13,701 individual members , who are professional astronomers from 102 countries worldwide; 81.7% of individual members are male, while 18.3% are female. Membership also includes 82 national members , professional astronomical communities representing their country's affiliation with
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1344-539: The Union's history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents and General Secretaries. Twelve of the fourteen past General Secretaries in the period 1964–2006 contributed their recollections of the Union's history in IAU Information Bulletin No. 100. Six past IAU Presidents in the period 1976–2003 also contributed their recollections in IAU Information Bulletin No. 104. In 2015 and 2019,
1386-648: The Union, bringing the total membership to 19 countries. Although the Union was officially formed eight months after the end of World War I, international collaboration in astronomy had been strong in the pre-war era (e.g., the Astronomische Gesellschaft Katalog projects since 1868, the Astrographic Catalogue since 1887, and the International Union for Solar research since 1904). The first 50 years of
1428-673: The Working Group for Planetary System Nomenclature (WGPSN), which maintains the astronomical naming conventions and planetary nomenclature for planetary bodies, and the Working Group on Star Names (WGSN), which catalogues and standardizes proper names for stars. The IAU is also responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams . The Minor Planet Center also operates under
1470-859: The comet would reappear only after 60,000 years. The International Astronomical Union officially named the comet as the Bappu-Bok-Newkirk comet (C/1949N1). Bappu also received the Donohoe Comet Medal of the Astronomical Society of the Pacific . This is the only comet with an Indian name. Vainu Bappu was born on 10 August 1927, in Chennai , as the only child of Manali Kukuzhi Bappu and Kallat Sunanna Bappu. His family originally hails from Thalassery in Kerala . His father
1512-472: The frozen nucleus of ice and dust, and an object when describing the entire comet with its diffuse coma and tail . Astronomical objects such as stars , planets , nebulae , asteroids and comets have been observed for thousands of years, although early cultures thought of these bodies as gods or deities. These early cultures found the movements of the bodies very important as they used these objects to help navigate over long distances, tell between
1554-679: The masses of binary stars based on their orbital elements . Computers began to be used to observe and study massive amounts of astronomical data on stars, and new technologies such as the photoelectric photometer allowed astronomers to accurately measure the color and luminosity of stars, which allowed them to predict their temperature and mass. In 1913, the Hertzsprung-Russell diagram was developed by astronomers Ejnar Hertzsprung and Henry Norris Russell independently of each other, which plotted stars based on their luminosity and color and allowed astronomers to easily examine stars. It
1596-635: The seasons, and to determine when to plant crops. During the Middle-Ages , cultures began to study the movements of these bodies more closely. Several astronomers of the Middle-East began to make detailed descriptions of stars and nebulae, and would make more accurate calendars based on the movements of these stars and planets. In Europe , astronomers focused more on devices to help study the celestial objects and creating textbooks, guides, and universities to teach people more about astronomy. During
1638-399: The various condensing nebulae. The great variety of stellar forms are determined almost entirely by the mass, composition and evolutionary state of these stars. Stars may be found in multi-star systems that orbit about each other in a hierarchical organization. A planetary system and various minor objects such as asteroids, comets and debris, can form in a hierarchical process of accretion from
1680-840: Was an astronomer at the Nizamiah Observatory in Telangana . He attended the Harvard Graduate School of Astronomy for his PhD after obtaining postgraduate degree from the Madras University . Bappu, along with two of his colleagues, discovered the 'Bappu-Bok-Newkirk' comet. He was awarded the Donhoe Comet-Medal by the Astronomical Society of the Pacific in 1949. In a paper published in 1957, American astronomer Olin Chaddock Wilson and Bappu had described what would later be known as
1722-592: Was found that stars commonly fell on a band of stars called the main-sequence stars on the diagram. A refined scheme for stellar classification was published in 1943 by William Wilson Morgan and Philip Childs Keenan based on the Hertzsprung-Russel Diagram. Astronomers also began debating whether other galaxies existed beyond the Milky Way , these debates ended when Edwin Hubble identified
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1764-473: Was used to improve the heliocentric model. In 1584, Giordano Bruno proposed that all distant stars are their own suns, being the first in centuries to suggest this idea. Galileo Galilei was one of the first astronomers to use telescopes to observe the sky, in 1610 he observed the four largest moons of Jupiter , now named the Galilean moons . Galileo also made observations of the phases of Venus , craters on
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