Difference between revisions of "Astronomical Unit"

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An '''astronomical unit''' (AU) is the average distance between the Earth and the Sun. It is defined as exactly 149,597,871 km, and equals approximately 8.3 [[Light-minute|light-minutes]]. The unit is most commonly used to measure distances within our and other solar systems.<ref>McClure, Brian. 2017. [https://earthsky.org/space/what-is-the-astronomical-unit “What Is an Astronomical Unit?”] EarthSky. October 23, 2017. </ref>
  
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An '''Astronomical Unit''' (AU) is most often used to measure distances within the Solar System. One astronomical unit is approximately  the distance between the Earth and the Sun but is defined as exactly 150 million km (150'000'000 km).
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[[Mars]] is about 1.5 AU from the Sun, which means it is 1.5 times the distance from the [[Earth]] to the Sun, or approximately 224 million km from the Sun (149,597,871 km • 1.5).
  
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For example Mars is about 2.5 AU from the Sun, which means it is 2.5 times the distance from the Earth to the Sun, or approximately 375 million km from the Sun (i.e. 150'000'000 km * 2.5).
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The distance from Earth to Mars varies from a little under 0.5 AU, to 2.5 AU, depending if the Earth is on the same side of the Sun as Mars, or we are far apart with the Sun between us.
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==Distances to objects in solar system==
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{| class="wikitable" style="margin:left"
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|+ Distances to objects near the Sun
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|-
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! Body !! Average Distance to Sun
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|-
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| '''SUN''' || 0 AU
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|-
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| '''Mercury''' || 0.4 AU
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|-
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| '''Venus''' || 0.7 AU
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|-
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| '''Earth''' || '''1.00 AU''' (by definition)
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|-
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| '''Mars''' || 1.52 AU
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|-
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| Vesta || 2.36 AU
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|-
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| Pallas || 2.77 AU
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|-
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| Ceres || 2.8 AU
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|-
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| Asteroid Belt || ~2 to ~4 AU
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|-
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| '''Jupiter''' || 5.2 AU
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|-
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| '''Saturn''' || 9.6 AU
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|-
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| '''Uranus''' || 19.2 AU
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|-
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| '''Neptune''' || 30.0 AU
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|-
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| Pluto || 39.5 AU
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|-
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| Haumea || 43.2 AU
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|-
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| Quaoar || 43.6 AU
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|-
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| Eris || 67.8 AU
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|-
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| Sedna || 489 AU
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|-
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| Kuiper belt || ~30 to ~50 AU
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|-
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| Scattered disk || ~100 to ~1,000 AU
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|-
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| Inner Oort Cloud || (~disk shaped) Inner edge ~2,000 to ~5,000 AU; outer edge ~20,000 AU.
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|-
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| Outer Oort Cloud || (spherical)  ~20,000 to ~200,000 AU ?
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|-
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| Proxima Centauri || ~268,770 AU or 4.246 light years (the nearest star).
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|}
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==References==
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<references />

Latest revision as of 16:21, 29 October 2024

An astronomical unit (AU) is the average distance between the Earth and the Sun. It is defined as exactly 149,597,871 km, and equals approximately 8.3 light-minutes. The unit is most commonly used to measure distances within our and other solar systems.[1]

Mars is about 1.5 AU from the Sun, which means it is 1.5 times the distance from the Earth to the Sun, or approximately 224 million km from the Sun (149,597,871 km • 1.5).

The distance from Earth to Mars varies from a little under 0.5 AU, to 2.5 AU, depending if the Earth is on the same side of the Sun as Mars, or we are far apart with the Sun between us.

Distances to objects in solar system

Distances to objects near the Sun
Body Average Distance to Sun
SUN 0 AU
Mercury 0.4 AU
Venus 0.7 AU
Earth 1.00 AU (by definition)
Mars 1.52 AU
Vesta 2.36 AU
Pallas 2.77 AU
Ceres 2.8 AU
Asteroid Belt ~2 to ~4 AU
Jupiter 5.2 AU
Saturn 9.6 AU
Uranus 19.2 AU
Neptune 30.0 AU
Pluto 39.5 AU
Haumea 43.2 AU
Quaoar 43.6 AU
Eris 67.8 AU
Sedna 489 AU
Kuiper belt ~30 to ~50 AU
Scattered disk ~100 to ~1,000 AU
Inner Oort Cloud (~disk shaped) Inner edge ~2,000 to ~5,000 AU; outer edge ~20,000 AU.
Outer Oort Cloud (spherical) ~20,000 to ~200,000 AU ?
Proxima Centauri ~268,770 AU or 4.246 light years (the nearest star).

References

  1. ↑ McClure, Brian. 2017. “What Is an Astronomical Unit?” EarthSky. October 23, 2017.
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