Why does the moon do this---?

Question

why does the moon move across the sky and why are there different phases??

Answer 1

The moon moves across the sky because the Earth rotates. The moon goes through many phases because it is circling around the earth and the earth casts a shadow on the moon depending on the position of the moon and the sun.

Answer 2

The moon moves across the sky for the same reason every other celestial object moves across the sky; the Earth is rotating.

The phases of the Moon are NOT caused by the Earth's shadow. The Moon is a sphere. Given a single source of illumination -- the Sun -- it is only possible to illuminate one half of a sphere. The phases of the Moon are caused by the shadow it casts on itself.

The Moon revolves around the Earth every 29.5 days. During that revolution, the illuminated side always faces the Sun -- obviously -- so we get a different perspective of its light and dark sides throughout the course of a month. Those are the phases of the Moon.

Answer 3

It moves across the sky during the day because of Earth's rotation, the same as the sun. It's in a different part of the sky each day and night because of it's revolution AROUND the Earth, which also gives us the phases.

Now look at this.

http://www.opencourse.info/astronomy/introduction/04.motion_moon/

The first picture on this link shows the moon at different parts of its orbit around Earth, with the sun to the left shining on the left of the Earth and moon.

When it's new moon, you can see that the lit side of the moon faces away from Earth. We can't see it then.

At the phase called waxing crescent, you can see it has moved part of the way around. It can be seen from the day side of the Earth (and a bit of the night side), but we can only see part of the lit side. The rest is still facing away from us. Much of the unlit side is facing us, so we only see a crescent of the lit side.

At first quarter (or half moon), we can see half of the lit side (the other part of the lit side faces away), and it's visible from half the day side of Earth and half the night side (in other words, it rises about midday and sets about midnight).

At full moon, the lit side is fully visible to us, because it's on the other side of the Earth from the sun.

And so on.

Answer 4

The moon moves across the sky because it orbits Earth while at the same time Earth rotates. The phases of the moon are caused by Earth's shadow falling on it. This shadow changes daily due to the motion of the moon around Earth.

Answer 5

The moon moves relative to the Sun as it makes one complete spin.
However frpm Earth reference frame we see an apparent motion of the moon. Its is acturally the Earth that is moving and spinnng. So What we observe is the relative motion of the moon as observed from the Earth. during the 24 hours day that the earth is spinning on itself. The Phases of the moon are basically the relative shadows of the earth on the moon when the Sun shines on the earth.
The phases are not discrete but move slowly over time.