Let us take one step back ...

Oh, look, an Eclipse!

(yes, my stick figures are as bad as my circles)

Eclipses

Lunar Eclipse (around 100 minutes)

When the Earth passes directly between the Sun and the Moon.

Lunar Eclipse

Moon appears redish due to sunlight deflected by Earths atmosphere onto the moons surface.

When the Moon passes directly between the Sun and the Earth.

Solar Eclipse (no more than about 8 minutes)

Total Solar Eclipse

By pure chance the sun and moon have almost the same angular size as seen from Earth – how can this be?

During which phase(s) can a lunar eclipse occur?

What about a solar eclipse?

Why don't eclipses occur every month?

Moon's orbit tilted compared to Earth-Sun orbital plane:

SunEarth

Moon

Side view

5.2o

Orbits “cross” here

And here

1 month

1 year

5o

But evey now and again the orbits of the Moon and Sun “cross” as they appear from Earth

How Often do Eclipses Occur?

Lunar eclipses occur more often than solar eclipses. In addition, when an eclipse of the Moon takes place, everyone on the night side of Earth can see it.

They can only occur:1) during the full phase of the moon,and2) if the line of intersection between the plane of Earth's orbit around the sun and the plane of the moons orbit around the Earth lie along the Earth-Sun line.

Two to four times each year, the Moon passes through some portion of the Earth's shadow and some type of Lunar eclipse occurs (total, partial, or penumbral = ”faint outer shadow”).

Solar eclipses occur less often then Lunar eclipses. When a solar eclipse occurs only a small portion of the Earth will see it. (You'd have to wait an average of 375 years to see two total eclipses from one place!)

They can only occur:1) during the new phase of the moon,and2) if the line of intersection between the plane of Earth's orbit around the sun and the plane of the moons orbit around the Earth must lie along the Earth-Sun line.

Just one total eclipse occurs each year or two.

Questions about Eclipses?