astronomical unit (AU)

astronomical unit (AU)
Length of the semimajor axis of Earth's orbit around the Sun, 92,955,808 mi (149,597,870 km), often defined simply as the average distance from Earth to the Sun.

Direct measurement through the parallax method cannot be used for accurate determinations, because the Sun's glare blots out the light of the background stars necessary to make the measurement. The most precise values have been obtained by measuring the distance from Earth to other objects orbiting the Sun. This indirect method requires an accurate proportional mathematical model of the solar system; once the distance to one planet or other object is determined, then the distance to the Sun can be calculated.

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Universalium. 2010.

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  • astronomical unit — n. Astron. a unit of length based on the mean distance of the earth from the sun, c. 149.6 million km ( c. 93 million mi): light travels this distance in c. 8.3 minutes: abbrev. AU …   English World dictionary

  • Astronomical unit — This article is about unit of length. For the full system of units, see Astronomical system of units. 1 astronomical unit = SI units 149.60×10^6 km 149.60×10^9 m Astronomical units 4.8481 …   Wikipedia

  • astronomical unit — Astron. a unit of length, equal to the mean distance of the earth from the sun: approximately 93 million miles (150 million km). Abbr.: AU [1900 05] * * * ▪ unit of measurement        Comparative data for the Sun, planets, and other solar system… …   Universalium

  • astronomical unit — (ua or au or AU)    a unit of distance used by astronomers to measure distances in the Solar System. One astronomical unit equals the average distance from the center of the Earth to the center of the Sun (mathematically, it is the length of the… …   Dictionary of units of measurement

  • astronomical unit — UK / US noun [countable] Word forms astronomical unit : singular astronomical unit plural astronomical units astronomy a unit for measuring distance in space …   English dictionary

  • Astronomical Unit — noun a unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers) (Freq. 1) • Syn: ↑AU • Hypernyms: ↑astronomy unit * * *… …   Useful english dictionary

  • Astronomical Unit —    A unit of distance used to measure orbits and trajectories within the solar system. An Astronomical Unit is the average distance between the Sun and Earth. One AU is roughly equal to 149,600,000 km (92,956,000 mi.). To give you an idea of the… …   The writer's dictionary of science fiction, fantasy, horror and mythology

  • astronomical unit — astronominis vienetas statusas T sritis Standartizacija ir metrologija apibrėžtis Apibrėžtį žr. priede. priedas( ai) Grafinis formatas atitikmenys: angl. astronomical unit vok. astronomische Einheit, f rus. астрономическая единица, f pranc. unité …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • astronomical unit — astronominis vienetas statusas T sritis fizika atitikmenys: angl. astronomical unit vok. Astronomische Einheit, f rus. астрономическая единица, f pranc. unité astronomique, f …   Fizikos terminų žodynas

  • astronomical unit — unit of distance equal to the distance from the earth to the sun Units of Measurement …   Phrontistery dictionary

  • astronomical unit — /ˌæstrənɒmɪkəl ˈjunət/ (say .astruhnomikuhl yoohnuht) noun a unit, defined as 149 597 870 km, approximately equal to the mean distance between the centre of the earth and the centre of the sun, used as a unit of distance in astronomy. Symbol: AU… …  

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