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One light-year equals roughly 9.46 trillion kilometres travelled by light in a year. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

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Yes. It sits on the Space shelf, one of 1,090 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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Mondo Knows Facts

A light-year is a measure of distance rather than time

One light-year equals roughly 9.46 trillion kilometres travelled by light in a year

Despite having year in its name, a light-year is a unit of astronomical length. It represents the total distance that a beam of light travels through a vacuum in one Earth year, which equals approximately 9.46 trillion kilometres or nearly 5.88 trillion miles.

Where this comes from

Encyclopaedia Britannica

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: light year, distance, astronomy

A light-year is a measure of distance rather than time: the short answers

Where does this come from, and can I check it?: One light-year equals roughly 9.46 trillion kilometres travelled by light in a year. The figure is taken from Encyclopaedia Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a space fact?: Yes. It sits on the Space shelf, one of 1,090 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.