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Laser pulses fired from Earth measure lunar distance down to millimetres. The figure is taken from NASA Science, 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.

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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.

Mondo Knows Facts

Apollo astronauts left retroreflector mirrors on the Moon surface

Laser pulses fired from Earth measure lunar distance down to millimetres

During the Apollo 11, 14 and 15 lunar missions, astronauts placed corner-cube retroreflector arrays on the Moon's surface. Scientists routinely fire laser pulses from Earth observatories at these mirror arrays, measuring the round-trip flight time to calculate the Earth-Moon distance within millimetres.

Apollo 12 Mission image - View of part of the deployed Apollo Lunar Surface Experiment Package (ALSEP) (as12-47-6918) — NASA Johnson Space Center · Public domain · source

Where this comes from

NASA Science

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Tags: apollo, laser, moon

Apollo astronauts left retroreflector mirrors on the Moon surface: the short answers

Where does this come from, and can I check it?: Laser pulses fired from Earth measure lunar distance down to millimetres. The figure is taken from NASA Science, 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.