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What is an astronomical unit?

Answer:
150 million kilometers/93 million miles
An Astronomical unit is the standard distance between the earth and the sun.

It is about 149,597,870.691 kilometers (92,955,807.267 miles).

It is defined as the distance that an object would have a perfectly circular orbit of exactly 365.2568983 days (31,558,196.01312 seconds).

One light-year is ~63,241 AU, and one parsec is ~206,265 AU.
distance
The average distance from Sun to Earth. About 150 million kilometers. This distance is commonly used to compare distances within the Solar System.
the distance between the sun and the earth. 93 million miles
The Astronomical Unit or AU is the average distance between the Sun and the Earth over 1 Earth orbit. It is equal to 149,598,000 km.

In the other sense stars themselves are not generally considered in the singular but rather the Star System which sometimes consists of many stars.

Take the system Alpha Centauri. It is in fact 3 stars. Alpha Centauri A, Alpha Centauri B and Proxima Centauri.
First answer by Katz2. Last edit by Alexyuwen. Contributor trust: 22 [recommend contributor recommended]. Question popularity: 17 [recommend question].