The Moon drifts away from Earth about 3.8 cm every year
Laser ranging from Earth to reflectors left on the lunar surface shows the Moon creeping outward by roughly 3.8 centimeters per year — about the width of a few finger joints.
Tides are the culprit. Earth’s oceans and crust raise bulges that the Moon’s gravity tugs on; that interaction transfers angular momentum outward, lengthening our day and widening the orbit.
Over geologic time the change adds up. In the deep past the Moon sat closer and tides ran wilder — a reminder that even “fixed” night-sky landmarks are slowly rearranging.
Shahzad Mahota
The Moon drifts away from Earth about 3.8 cm every year
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