A total solar eclipse is only possible because of a cosmic coincidence: the Moon is about 400 times smaller than the Sun but also about 400 times closer, making the two look almost the same size from Earth. But the Moon is slowly drifting away, so this alignment will not last forever. One day, hundreds of millions of years from now, the last total solar eclipse will pass across the planet, and no one will ever see the Moon fully cover the Sun again.

A total solar eclipse rests on a coincidence that is simple to state and still hard to quite accept. The Sun is roughly 400 times wider than the Moon. At present it also sits roughly 400 times further away. The two therefore appear almost the same size from the ground, which is why the Moon [...] The post A total solar eclipse is only possible because of a cosmic coincidence: the Moon is about 400 times smaller than the Sun but also about 400 times closer, making the two look almost the same siz