Americans are a little spoiled when it comes to eclipses. After all, we’re about to experience one that the majority of the country will see, and it comes on the heels of the “Great American Eclipse” that tracked from Oregon to South Carolina in 2017.
But that doesn’t often happen. And it won’t again until the 2040s.
On average, an eclipse occurs in the same place every 375 years, said Dr. John Mulchaey, Carnegie Institution for Science’s deputy for science and the director and Crawford H. Greenewalt Chair of the Carnegie Observatories.
And we’re living at the right time to truly enjoy the sight of a total eclipse on Earth, he said.
While eclipses occur throughout the solar system, none are exactly like the ones experienced in our world.
The moon is about 400 times smaller than the sun, but the moon is also about 400 times closer to Earth than the sun is, creating a “beautiful coincidence” that results in eclipses when the three celestial bodies align, Mulchaey said.
This alignment is called syzygy, or when three objects line up in space.
In the distant past, the moon was much closer to Earth, which means totality likely didn’t appear as it does now. And within another 60 million years or so, the moon will be so far away that it will never cover the sun, making this a rare moment in time, Mulchaey said.
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