Lunar Phases

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Who on Earth will be able to see a lunar eclipse?

Anyone who can see the Moon (anyone who is on the nighttime side of the Earth during the eclipse)

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Images from Fred Espenak

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Why is the Moon red during an eclipse?

The Earth’s atmosphere filters some sunlight and allows it to reach the Moon’s surface

The blue light is removed—scattered down to make a blue sky over those in daytime

Remaining light is red or orange

Some of this remaining light is bent or refracted so that a small fraction of it reaches the Moon

Exact appearance depends on dust and clouds in the Earth’s atmosphere

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Solar Eclipses

When the Moon’s shadow covers part of the Earth

Only happens at New Moon

Three types: Annular, Partial, and Total

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Total Solar Eclipse

Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can see the corona

Those in “penumbra” see a partial eclipse—not safe to look directly at Sun

Only lasts a few minutes

Path of Totality about 10,000 miles long, only 100 miles wide

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Annular Solar Eclipse

When the Moon is too far to completely cover the Sun—the umbra doesn’t reach the Earth

Sun appears as a donut around the Moon

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Photos of an Annular Eclipse

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Tides

The Moon’s gravity tugs on the Earth.

It pulls the most on the part of Earth closest, which raises the atmosphere, the oceans, and even the rocks (a little)

It pulls the least on the part of Earth that’s farthest, which allows the oceans and atmosphere to be further from the Moon (and higher)

The Sun’s gravity does the same thing, but to a lesser extent

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Tides and the Moon