The Moon Is Leaving Us?! Here’s How Fast—30 Facts
The Moon is slowly drifting away from Earth—about 3.8 cm per year —because tidal forces transfer a tiny bit of Earth’s spin into the Moon’s orbit. We measure this with lasers , watch it play out as tides , and even see its fingerprints in eclipses , ancient rocks , and the length of our day . Here’s the full story—plus 30 quick facts to make you a Moon expert. How We Know the Moon Is Moving Scientists fire laser pulses at retroreflector mirrors left on the Moon by Apollo astronauts and Soviet Lunokhod rovers. By timing the 2.5–2.7 second round trip of light, we track the Earth–Moon distance down to millimeters. That distance isn’t fixed: the Moon’s slightly elliptical orbit means it swings from perigee (closer) to apogee (farther) each month, centered around an average of ~385,000 km . When a full Moon lands near perigee, it looks bigger and brighter—hello, supermoon . Why the Moon Is Drifting Away It’s all about tides . The Moon pulls harder on Earth’s near side than ...