Magazine article The Elementary STEM Journal

2012 Was a Year of Eclipses

Magazine article The Elementary STEM Journal

2012 Was a Year of Eclipses

Article excerpt

When Earth and the Moon were very young, they were much closer together. The Moon was so close, it took up a huge part of Earth's sky. When it hung overhead in the daytime, it cast a big shadow on the Earth.

Over Earth's long history, the Moon has drifted a lot farther away. Now it just so happens that the Moon takes up almost exactly as much of the sky as the Sun does. That is because the Sun is 400 times wider (larger in diameter) than the Moon, but it is also 400 times farther away than the Moon. Isn't that awesome? What are the odds? Actually, nobody knows.

What this happy coincidence allows is a perfect total eclipse of the Sun. That means the Moon, when it is just in the right spot at the right time, can hide the Sun, exactly covering its disc. When this event happens, the Sun's corona, or atmosphere "pops out," looking like a broad halo of fire.

The Moon's orbit around Earth is not an exact circle, however. Sometimes it's a little closer to Earth than at other times. The closer it is, the bigger it looks to us. If a solar eclipse occurs when the Moon is farthest from Earth, the Moon looks smaller. …

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