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From our perspective on Earth, two types of eclipses occur: lunar, the blocking of the Moon by Earth's shadow, and solar, the obstruction of the Sun by the Moon. Each of these can be partial or total. There's a lot to learn about each type of eclipse and how eclipses happen, and once you know more about them, you're sure to find them even more awesome.
Interactions of the Moon, the Sun, and Earth are involved in both a solar eclipse and a lunar eclipse. When the moon moves between Earth and the sun, blocking the sun, it causes what we call a solar eclipse. When Earth is perfectly aligned between the moon and the sun, blocking the sun's light from reaching off the moon, we call it a lunar eclipse. It's important to note that while you can look up at the moon to see a lunar eclipse, you should never stare directly at the sun: If you want to see a solar eclipse, you'll need a special viewer to look through to protect your eyes.
The Tilt in the Moons Orbit
If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be solar and lunar eclipses every month. However, since the Moon's orbit is tilted about 5 degrees relative to the Earth's orbit around the Sun, it passes either above or below the line of sight to create an eclipse.
Total solar eclipses are the rarest of the solar eclipses. A solar eclipse can occur only when the Moon is close enough to the ecliptic plane during a new moon. A total solar eclipse can only be viewed along a narrow strip of Earth, called the path of totality; people outside of this area will see a partial eclipse or no eclipse at all.
Solar Eclipse Geometry
Total Solar Eclipse
Partial Solar Eclipse
Partial solar eclipses happen more frequently. We don't usually see them, though, because the sun is so bright that it's not that noticeable when a bit of it is blocked; a significant amount of the sun needs to be blocked before we can see the eclipse. Partial solar eclipses can be seen before a full eclipse or on their own.
Partial Solar Eclipse
Annular Solar Eclipse
Annular eclipses have a special charm all their own. Like a total solar eclipse it will only be witnessed by people in a small area. This type of eclipse will look like a ring of fire in the sky, as the moon is furthest away in its orbit and is not close enough to Earth to block all of the sun's light at once. There will be a significant darkening of the sky during an annular eclipse, but it will not be anywhere near as shockingly dark as it is during a total eclipse.
Annular Eclipse Geometry
Annular Solar Eclipse
Lunar eclipses can only happen when the Moon is opposite the Sun in the sky during a monthly occurrence we know as a full Moon. But lunar eclipses do not occur every month because the Moon's orbit is tilted five degrees from Earth's orbit around the Sun. Without the tilt, lunar eclipses would occur every month. During a total lunar eclipse, Earth's shadow covers the entire moon. If you watch a total lunar eclipse, you'll see Earth's shadow covering more and more of the moon until totality; at this point, the sun's light will actually be able to pass around Earth, through Earth's atmosphere, giving the moon an odd reddish hue..
Lunar Eclipse Geometry
Total Lunar Eclipses
During a total lunar eclipse, Earth's shadow covers the entire moon. If you watch a total lunar eclipse, you'll see Earth's shadow covering more and more of the moon until totality; at this point, the sun's light will actually be able to pass around Earth, through Earth's atmosphere, giving the moon an odd reddish hue.
Lunar Eclipse Geometry
Total Lunar Eclipse
Partial Lunar Eclipse
Partial lunar eclipses can lead up to a total eclipse or occur by themselves. In a partial lunar eclipse, the moon travels into Earth's shadow but is not fully covered by it. The moon will look partially dark as Earth's shadow passes over it.
Partial Lunar Eclipse
Penumbral Lunar Eclipse
Penumbral eclipses often go unnoticed, as they are simply a shading of part of the moon. In these situations, Earth casts a shadow on one side of the moon, but it's only the lighter edge of Earth's shadow, called the penumbra. The moon is still visible the entire time, but it might look a bit dimmer.
Lunar and solar eclipses occur with about equal frequency. Lunar eclipses are more widely visible because Earth casts a much larger shadow on the Moon during a lunar eclipse than the Moon casts on Earth during a solar eclipse. As a result, you are more likely to see a lunar eclipse than a solar eclipse.
SOLAR ECLIPSES
Solar eclipses occur at a rate of two to four times a year worldwide. But since the path of totality is fairly narrow, and the Moon's orbit is tilted 5 degrees relative to Earth, it's rare to be able to see a total solar eclipse without making a special trip somewhere else to see it. Visit our Solar Eclipse page to see upcoming solar eclipses.
LUNAR ECLIPSES
Lunar eclipses happen two to five times a year. A lunar eclipse is visible from a much larger section of Earth than a solar eclipse and stays visible for a longer time. While a total solar eclipse typically lasts a couple of minutes, a total lunar eclipse will last up to an hour or more, with a partial lunar eclipse happening over several hours.
Page Created by AAG, August 2021.