astronomical unit
astronomical unit (AU) A unit of length, formerly the mean distance of the Earth from the Sun, but now defined more technically, as below. In the original definition of the AU by C. F.
Gauss, the Earth's mean distance from the Sun (i.e. the semimajor axis of the Earth's orbit) was given by the precise form of Kepler's third law as found by Newton:n
2a
3 = k
2 (m + m
E),
where
n is the Earth's mean motion (in radians per day),
a is the semimajor axis of the Earth's orbit (in AU),
m and
mE are the masses of the Sun and Earth respectively (in solar masses), and
k is the
Gaussian gravitational constant. The astronomical unit is now defined as the distance from the Sun of a massless particle moving in a circular orbit around the Sun with an orbital period of one
Gaussian year of 2π/k ephemeris days. The Earth's mean distance from the Sun is 1.000 000 031 AU, where 1 AU × 149 597 870 km.
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Ulysses begins polar exploration. (spacecraft reaches destination of about 2.4 astronomical units below the sun's south pole) (Brief Article)
Magazine article from: Science News; 8/6/1994; 686 words
; ...Ulysses began in late June to study the star's polar regions. Through December, the craft will orbit about 2.4 astronomical units (AU) below the solar south pole; a similar sojourn above the north pole begins next June. (One AU is the average...
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Star tracks. (Thousand Astronomical Unit project)
Magazine article from: Science News; 2/28/1987; ; 700+ words
; ...limitation. Called TAU for Thousand Astronomical Unit project, the proposed flight...a telescope out to 1,000 astronomical units--1,000 times the mean...recent meeting of the American Astronomical Society in Pasadena. "Why...
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Let's have an eight-day week Unlike the day, month and year, which relate to astronomical cycles, the week is an arbitary unit
Newspaper article from: The Independent - London; 7/21/1999; ; 700+ words
; ...dictate a week of specific duration. Unlike the day, month and year, which correspond to the astronomical cycles, the week is an arbitrary unit of time. While the biblical account of the Creation makes reference to God's resting on the seventh...
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Analysis: New astronomical findings and the latest telescope technology
Transcript from: NPR Talk of the Nation Science Friday; 1/11/2002; ; 700+ words
; ...attended the national meeting of the American Astronomical Society in Washington, DC, this week, and...dwarf and its parent star is only about 14 astronomical units, or an astronomical unit is the distance from the Earth to the sun...
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World's most sensitive astronomical camera developed at the Universite de Montreal.
Newspaper article from: NewsRx Health & Science; 10/18/2009; 700+ words
; ...the world's most sensitive astronomical camera. Marketed by Photon...which purchased the first unit. The camera is made up of...amplifies photons observed by astronomical cameras or by other instruments...the weak signals coming from astronomical objects in the night sky...
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A (mis)understanding of astronomical proportions?(Perspectives: Research and tips to support science education)
Magazine article from: Science and Children; 9/1/2008; ; 700+ words
; ...scientific ideas included in our unit, students still hang onto...hold incorrect ideas about astronomical events? Often children...ideas based on their limited astronomical experiences and knowledge...elementary students about astronomical phenomena and found that relying...
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Astronomical calculations in ancient India based on scientific research
News Wire article from: The Hindustan Times; 12/7/2006; 527 words
; ...DELHI, India, Dec 7 -- "THE ASTRONOMICAL calculations made in ancient...intelligent being called Manu, is an astronomical unit of time denoting one cycle of...Such complicated and precise astronomical calculations also establish...
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Reflect action: BAE Systems adapts flexible astronomical telescope mirror to enable aircraft pilots to see more clearly. (News).
Magazine article from: The Engineer; 8/9/2002; ; 700+ words
; ...more clearly with a device adapted from astronomical telescopes. Defence and aerospace giant...site earlier this year, and different units in BAE Systems are taking turns to try...systems.' Originally developed for large astronomical telescopes and military spy satellites...
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 "The Economist (US)")
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Ringworlds.(highlights from the American Astronomical Society meeting)
Magazine article from: The Economist (US); 1/16/1999; 700+ words
; ...findings presented to the 1999 meeting of the American Astronomical Society (AAS). First, the planets . . . IF THE...spotted a tiny dot that looks like a planet some 150 astronomical units (AU) from the star. (1 AU is 150m kilometres...
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UNIVERSITY OF NORTH DAKOTA ASTRONOMICAL OBSERVATORY TO HOST COMMUNITY OPEN HOUSE ON AUG. 26
News Wire article from: US Fed News Service, Including US State News; 8/24/2006; 522 words
; ...Space Studies and the Northern Skies Astronomical Society - the astronomy club. UND operates...through telescopes - including several units of various sizes belonging to astronomy...UND faculty and students conducting astronomical research and with experienced amateur...
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Astronomical unit
Encyclopedia entry from: The Gale Encyclopedia of Science
...within the solar system. One astronomical unit is the mean (average...000 km). The value of the astronomical unit has been measured by various...the sun and the planets, in astronomical units, were known long before the...
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astronomical unit
Book article from: The Columbia Encyclopedia, Sixth Edition
astronomical unit (AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e...
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International System of Units
Book article from: Chemistry: Foundations and Applications
...modifications of scientific units. The metric system was established...1832 added the second as the unit of time. The British Association...known as the CGS system, whose units of measure were the centimeter...meter and kilogram and the astronomical second as the unit of time. Fifty years ...
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unit distance
Book article from: A Dictionary of Astronomy
...distance A distance taken as a convenient unit of length. Within the Solar System the unit distance is the astronomical unit ( AU ), the average distance of the...the parsec (pc) is used. Larger units such as the kiloparsec (1000 ...
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Astronomy, Measurements in
Book article from: Mathematics
...measurements were fairly accurate. Modern Astronomical Measurement The modern period of astronomical measurement began with Nicolaus Copernicus...Kepler defined this measurement to be 1 astronomical unit (1 AU). Using trigonometric ratios...
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