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Astronomical unit

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Credit to Huritisho

The astronomical unit (au or AU)[1] is a unit of distance used in astronomy to measure the distances in space. It is equivalent to the median distance between the Earth and the Sun, approximately 149 597 870.7 kilometers. [1]

Examples of usage[edit]

References can be found on each individual object's own page.

Object Diameter in astronomical units Comments and reference points
Earth's circumference 0.0003 The circumference of Earth at the equator.
Light second 0.002  The distance light travels in one second is 299,792 km.
Lunar distance 0.0026 The Moon is 384,000 kilometers away from Earth at median.
Solar radius

(Half of the Sun's diameter)

0.005  The radius of the Sun is 696,392 kilometers.
Light minute 0.12   The distance light travels in one minute is 17,987,520 kilometers.
Mercury 0.39   Median distance from the Sun
Venus 0.72  
Earth 1.00  
Mars 1.52  
Ceres 2.77   The only dwarf planet in the asteroid belt.
Jupiter 5.20   Median distance from the Sun
Light hour 7.2    The distance light travels in one hour is approximately 1,079,251,200 kilometers.
Betelgeuse 8.8 Ninth brightest star in the night sky. Diameter is 950 times greater than the Sun's.
Saturn 9.58   Median distance from the Sun
VV Cephei A 17.7 One of the largest known stars
Uranus 19.23   Median distance from the Sun
VY Canis Majoris 20.5 The largest known star
Kuiper belt 30      The boundaries of the Kuiper belt begins at roughly that distance from the Sun.
Neptune 30.10   Median distance from the Sun
New Horizons 38.10   The spacecraft's current distance from the Sun.
Pluto 39.3    Median distance from the Sun
Scattered disc 45      It roughly begins at that distance from the Sun.
Kuiper belt 50      ends at that distance from the Sun
Eris 67.8    Median distance from the Sun
90377 Sedna 76      Distance at the perigee.
Light day 173    The distance light travels in one day is 2 590 000 000 kilometers.
Light year 63241 The distance light travels in approximately one Julian year is 9.47 trillion kilometers.
Proxima Centauri 268000 Closest star to the Sun.

References[edit]


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