* Astronomical models, such as orreries whose history spans hundreds of years.

Astronomical measurements of both matter-energy density of the universe and spacetime intervals using supernova events constrain the spatial curvature to be very close to zero, although they do not constrain its sign.

Astronomical objects or celestial objects are naturally occurring physical entities, associations or structures that current science has demonstrated to exist in the observable universe.

Fowler won the Henry Norris Russell Lectureship of the American Astronomical Society in 1963, the Vetlesen Prize in 1973, the Eddington Medal in 1978, the Bruce Medal of the Astronomical Society of the Pacific in 1979, and the Nobel Prize for Physics in 1983 for his theoretical and experimental studies of the nuclear reactions of importance in the formation of the chemical elements in the universe ( shared with Subrahmanyan Chandrasekhar ).

After the UTSO was closed, in 1998 the Canadian Astronomical Society, a society of university astronomers, published a long range plan emphasizing the study of the origins of structure in the universe, a task well-suited to cutting-edge telescopes but ill-suited to the DDO.

Though the universe might in theory have a longer history, the International Astronomical Union presently use " age of the universe " to mean the duration of the Lambda-CDM expansion, or equivalently the elapsed time since the Big Bang in the current observable universe.

At a conference of the International Astronomical Union in Rome in 1952, he presented results of studies of variable stars in the Magellanic Clouds, indicating that the perceived age and size of the universe had to be doubled.

Together with fellow staff-member Kent Ford, Rubin announced at a 1975 meeting of the American Astronomical Society the discovery that most stars in spiral galaxies orbit at roughly the same speed, which implied that their mass densities were uniform well beyond the locations with most of the stars ( the galactic bulge ), a result independently found in 1978.

High-precision ephemerides of sun, moon and planets were developed and calculated at the Jet Propulsion Laboratory ( JPL ) over a long period, and the latest available were adopted for the ephemerides in the Astronomical Almanac starting in 1984.

Although a number of the larger members of this group were initially described as planets, in 2006 the International Astronomical Union reclassified Pluto and its largest neighbours as dwarf planets, leaving only eight planets in the Solar System.

Pluto and Eris were eventually classified as dwarf planets by the International Astronomical Union.

Historical Julian dates were recorded relative to GMT or Ephemeris Time, but the International Astronomical Union now recommends that Julian Dates be specified in Terrestrial Time, and that when necessary to specify Julian Dates using a different time scale, that the time scale used be indicated when required, such as JD ( UT1 ).

In 1990, the Orbital Mechanics Department and Astronomical Applications Department were established, and Nautical Almanac Office became a division of the Astronomical Applications Department.

Seidelmann until 1994 when the department was abolished, and its functions were moved to a group within the Astronomical Applications Department.

The Babylonian Chronicles and Astronomical Diaries record several attempts to rebuild the Etemenanki, which were always preceded by removing the last debris of the original ziggurat.

Successful lunar laser range measurements to the retroreflectors were first reported by the 3. 1m telescope at Lick Observatory, Air Force Cambridge Research Laboratories Lunar Ranging Observatory in Arizona, the Pic du Midi Observatory in France, the Tokyo Astronomical Observatory, and McDonald Observatory in Texas.

The same results were independently arrived at by Adolf Berberich of the Königliches Astronomisches Rechen Institut ( Royal Astronomical Computation Institute ) in Berlin, Germany.

Together with fellow staff-member Kent Ford, Rubin announced at a 1975 meeting of the American Astronomical Society the discovery that most stars in spiral galaxies orbit at roughly the same speed, which implied that their mass densities were uniform well beyond the location with most of the stars ( the galactic bulge ), a result independently found in 1978.

To elevate astronomical science the Astronomical Society of London was founded, and the three reformers Peacock, Babbage and Herschel were again prime movers in the undertaking.

In 1835, along with Mary Somerville, she was elected to honorary membership of the Royal Astronomical Society ; they were the first honorary women members.

The names of all seven then-known satellites of Saturn, including Mimas, were suggested by William Herschel's son John in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope.

The journal and the supplement series were both published by the University of Chicago Press for the American Astronomical Society.

The final images were released at a meeting of the American Astronomical Society in January 1996, and revealed a plethora of distant, faint galaxies.

The coordinates were speedily sent out as an International Astronomical Union ( IAU ) and Gamma-ray burst Coordinate Network Circular.

Observations are currently being coordinated by the Association of Lunar and Planetary Observers and the British Astronomical Association to re-observe sites where transient lunar phenomena were reported in the past.

The results were published in 1885 in his Uranometria Nova Oxoniensis, and their importance was recognized by the bestowal in 1886 upon him, conjointly with Professor Pickering, of the Gold Medal of the Royal Astronomical Society.

TDT and TDB were defined in a series of resolutions at the same 1976 meeting of the International Astronomical Union.

" In a later larger survey conducted among the members of the American Astronomical Society, where 2611 were questionnaires mailed and 1356 were returned, Sturrock found out that opinions were equally diverse, with 23 % replying " certainly ", 30 % " probably ", 27 % " possibly ", 17 % " probably not ", and 3 % " certainly not ", to the question of whether the UFO problem deserves scientific study.

The 1976 definition of the astronomical unit was incomplete, in particular because it does not specify the frame of reference in which time is to be measured, but proved practical for the calculation of ephemerides: a fuller definition that is consistent with general relativity was proposed, and " vigorous debate " ensued until in August 2012 the International Astronomical Union adopted the current definition of 1 astronomical unit = 149597870700 meters.

He founded the Uppsala Astronomical Observatory in 1741, and in 1742 he proposed the Celsius temperature scale which takes his name.

In 1822, Charles Babbage proposed the use of such a machine in a paper to the Royal Astronomical Society on 14 June entitled " Note on the application of machinery to the computation of astronomical and mathematical tables ".

Beech and Steel, writing in Quarterly Journal of the Royal Astronomical Society, proposed a new definition where a meteoroid is between 100 µm and 10 m across.

In 1951, at a meeting of the Royal Astronomical Society, Gold proposed that the source of recent radio signals detected from space was outside the Milky Way galaxy, much to the derision of radio astronomer Martin Ryle and several mathematical cosmologists.

At the International Astronomical Union ( IAU ) meeting in Dublin in 1955, he had proposed the system of distinguishing between variants of Universal Time, as UT0 ( UT as directly observed ), UT1 ( reduced to invariable meridian by correcting to remove effect of polar motion ) and UT2 ( further corrected to remove ( extrapolated ) seasonal variation in earth rotation rate ), a system which remains in some use today.

Names of major surface features were proposed by Hayabusa scientists and accepted by the Working Group for Planetary System Nomenclature of the International Astronomical Union.

Hardly believing a second discovery so soon after the first, Hyakutake reported his observation to the National Astronomical Observatory of Japan the following morning.

At first, the journal articles available via ADS were scanned bitmaps created from the paper journals, but from 1995 onwards, the Astrophysical Journal began to publish an on-line edition, soon followed by the other main journals such as Astronomy and Astrophysics and the Monthly Notices of the Royal Astronomical Society.

Ephemeris time based on the standard adopted in 1952 was introduced into the Astronomical Ephemeris ( UK ) and the American Ephemeris and Nautical Almanac, replacing UT in the main ephemerides in the issues for 1960 and after.

The International Astronomical Union honored him by naming an asteroid after him, 6471 Collins.

Shortly after NASA was formed, the Orbiting Solar Observatory was launched, and was followed by the Orbiting Astronomical Observatory ( OAO ) that carried out ultraviolet observations of stars between 1968 and 1972.

The astronomical day was shifted from noon, twelve hours after midnight, to midnight effective by a resolution of the newly formed International Astronomical Union.

In 1985, the International Astronomical Union's Working Group for Planetary System Nomenclature honoured Frances Moore Brooke by naming a crater after her on the surface of the planet Venus.

In 2006, the International Astronomical Union ( IAU ) named a continent-sized area of Saturn's moon Titan as Xanadu after it was referred from Coleridge's poem.

; Astronomical dawn: the moment after which the sky is no longer completely dark ; formally defined as the time at which the sun is 18 degrees below the horizon in the morning.

* Astronomical Publishing in Edinburgh in the 19th Century ( implies he founded " Carrubbers Close Mission " after 1874 )

In 1976, the International Astronomical Union's Working Group for Planetary System Nomenclature ( IAU / WGPSN ) officially adopted the name Banff for a crater on Mars, after the town in Alberta.

Slater describes the dedication of the Laboratory, the hosting of meetings of the International Astronomical Union, the American Physical Society, and a Spectroscopic conference, and ends: " In general the year has been one of settling down to work under satisfactory conditions, after the more difficult transition of the preceding year.

However, it is hoped that the International Astronomical Union will make permanent the names of certain major features, such as the Columbia Hills, which were named after the seven astronauts who died in the Space Shuttle Columbia disaster.

* The Royal Astronomical Society of Canada has a writing award named after him.

Named after him are lunar impact crater Urey, asteroid 4716 Urey and the H. C. Urey Prize, awarded for achievement in planetary sciences by the American Astronomical Society.

* Astronomical objects named after people

Under the guidelines of the International Astronomical Union's naming conventions, objects with a similar size and orbit to that of Pluto are named after underworld deities.

" Brown also suggested to the International Astronomical Union's ( IAU ) Minor Planet Center that any future objects discovered in Sedna's orbital region should also be named after entities in arctic mythologies.

* Astronomical clock, 1464 – 1470, Hans Düringer of Toruń, reconstructed after 1945

In 1997 the International Astronomical Union named a minor planet orbiting the sun between Mars and Jupiter after him.

* Astronomical objects named after people

A small planetoid is named after Wubbo Ockels by the International Astronomical Union.

The Bruce Medal of the Astronomical Society of the Pacific is named after her, as well as the asteroid 323 Brucia, and the crater Bruce on the Moon.

According to the citation for an asteroid named after him, 29824 Kalmancok, " He significantly contributed to building the Comenius University Astronomical and Geophysical Observatory in Modra.

OAFA is named after Félix Aguilar ( 1884 – 1943 ), an Argentine astronomer and engineer who was director of the La Plata Astronomical Observatory from 1919 to 1921, and again from 1934 until his death.