Hook

Their other posts in the index, biggest breakout first.
The Moon's Slow Goodbye is drifting away from us. It's drifting about 4 centimeters per year. Roughly the rate your fingernails grow. We know that because astronauts left mirrors on the Moon. We shoot lasers at them and time how long it takes for them to come back. And it's getting longer. So why is the Moon leaving? Blame the tides. The Moon's gravity pulls Earth's oceans into a bulge. But Earth spins faster than the Moon orbits, so that bulge gets dragged ahead of the Moon and tugs it forward, flinging it into a slightly wider orbit. Billions of years ago, the Moon was much closer and looked larger in our sky. Today the Moon and the Sun look exactly the same size, which is why we get perfect solar eclipses. About 600 million years from now, Earth will have its last total eclipse ever fully. Will the Moon ever fully leave us? No. Before that, the Sun will swell into a red giant and swallow us both.