What is the Distance to the Moon and How is it Measured?

-- | April 21, 2016

Question: What is the true distance of the moon from the surface of the earth, since VLT @ Paranal can shoot a high powered laser to measure the distance? Based on surface temperatures recorded by NASA, it appears to be much closer than stated and potentially within the middle thermosphere.  — Robert

Answer: From the nice description of the Moon’s distance from us provided by the Universe Today, the average distance to the Moon is on average 384,403 kilometers, which is about 238,857 miles.  This distance is routinely measured using LIDAR (LIght Detection And Ranging) stations which bounce laser pulses off of the retroreflecting mirrors placed on the Moon by the Apollo astronauts.  I am not aware of a LIDAR installation at the Very Large Telescope (VLT) observatory in Chile.  The accuracy of these measurements is a few millimeters, which has allowed scientists to determine that the Moon is slowly moving away from us at a rate of about 3.8 cm (about 1.5 inches) per year.

Jeff Mangum