Planetary Video

Solar eclipses explained

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An eclipse is a celestial event that happens when a planet, a moon, and a star line up in a specific way. When the Moon is in the middle of the lineup, you get a solar eclipse. As the Moon blocks the light of the Sun, a giant Moon shadow covers parts of the Earth, resulting in some astonishing visual experiences.

Transcript

A total solar eclipse. It's one of the best space experiences you can have while still on Earth. An eclipse is a celestial event that happens when a planet, a moon, and a star line up in a specific way. When the Moon is in the middle of the lineup, you get a solar eclipse. As the Moon blocks the light of the Sun, a giant moon shadow covers parts of the Earth resulting in some astonishing visual experiences.

If the Moon orbited the Earth on a perfectly flat plane, there would be a total solar eclipse every 29 and a half days. However, the Moon's path around us is slightly tilted. Often, the shadow of the Moon extends out into space, completely missing the Earth. This makes solar eclipses much more rare and creates some variety in how they appear.

For some eclipses, the Moon will only cover part of the Sun, like this. We call this a partial eclipse. It could look like a tiny nibble out of the edge. Or it might appear as a crescent Sun. Either way, partial eclipses must be viewed with proper eye protection the entire time. Even if more than half of the Sun is covered it can still damage your eyes if you look at it without eclipse safety glasses. If you're lucky, when an eclipse comes, you might be in the path of totality. That means you have a special opportunity. As the Moon and Earth orbit, revolve, and rotate around in their constant cosmic dance, occasionally things line up just right and the Moon will completely block the Sun in the sky. This is a total solar eclipse.

During the moments of totality, the sky will get so dark that you might be able to see stars in the daytime. And swirling and waving around the outside edges of the moon, the elusive solar corona can be seen even with the naked eye. It is remarkable that our giant Sun is 150 million kilometers away, but our little Moon is just the right size and distance to completely cover it. We're lucky here on Earth. It doesn't always work perfectly that way. On Mars, for example, the moon Phobos is too small to block out the Sun.

Even on Earth, not every total eclipse is the same. Both the Moon's orbit and the Earth's orbit are somewhat elliptical, which makes the distances between the Earth, the Moon, and the Sun vary. This change in distance also changes the apparent sizes of the Moon and Sun as we see them from Earth. So if a total eclipse happens while the Moon is farther from Earth, the Moon won't cover everything since it appears slightly smaller than the Sun in our sky. When this happens, it's called an annular eclipse and it looks like a fiery ring of light.

We humans have been entranced by eclipses as far back as you can imagine. If you get a chance to see a solar eclipse, take advantage of it. Many report the experience to be breathtaking and even life-changing. To learn more about all different kinds of eclipses visit planetary.org in the link provided.