Astronomical unit
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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
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. |