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|Noun||1.||astronomy unit - a linear unit used for astronomical distances|
light year, light-year - the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers
light hour - the distance light travels in a vacuum in one hour; approximately one billion kilometers
light minute - the distance light travels in a vacuum in one minute; approximately 18 million kilometers
light second - the distance light travels in a vacuum in one second; approximately 300,000 kilometers
Astronomical Unit, AU - 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)