Where does the moon cast a shadow?

Answer 1

The Moon is always casting a "shadow" except for when it is being eclipsed by the Earth. Most of the time, the shadow doesn't land anywhere. Only when the Moon comes between the Sun and something else does it truly "cast a shadow" on something. Usually, this 'something else' is the Earth.

The Moon's shadow has several parts to it. The reason is that the source of light, the Sun, is actually larger than the Moon.

The darkest part is called the umbra. This is a cone-shaped shadow - the base being the Moon itself, and the tip pointing directly away from the sun. Inside this cone, the Moon appears larger to the observer than the Sun, so it completely blocks out the sunlight.

The penumbra is a partial shadow where the Moon appears to partially cover the sun.

The antumbra is another part of the shadow that is cone shaped. The tip of this shadow is the same point as the tip of the umbra, with the base pointing away from the Moon. (getting wider as it goes). If you fall inside of this shadow, the Moon will be a dark circle completely inside the Sun, but the Sun appears larger than the Moon, so you see a ring of Sun around the Moon.

(see the pictures of these on the reference page below)

The reason solar eclipses are so rare at any given location is that the shadow cast by the Moon is very small on the Earth. The Moon's orbit is inclined to the plane of the Earth's orbit, so it tends to wobble 'above' and 'below' the Sun, as viewed from Earth. Also, the Moon's distance varies, so sometimes it is too far from Earth for the umbra (total eclipse) to reach the Earth at all.

Also remember that more of the Earth's surface is water than land, and all of the land isn't inhabited, so that's why it's so rare to see a solar eclipse in any given location.

If you were in a space ship orbiting the Moon, it would cast a shadow on you every time you went around the side facing away from the Sun.

Answer 2

On anything that the moon gets between it and the sun. When the moon casts a shadow on the Earth it is called a solar eclipse.