What is directly responsible for the phases of the moon?

Answer 1

I think its the variable distance between the moon and earth

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Nope. 50% of the moon is always illuminated by the sun. But the moon travels

its orbital path around the Earth, roughly once a month. So the amount of the

lighted half that we can see from our position is always changing.

Answer 2

The Earth is orbiting the Sun while the Moon orbits the Earth. The Moon's cycle takes 29.5 days, from full moon to full moon.

At the full moon, the Moon is on the opposite side of the Earth from the Sun, and the entire illuminated face of the Moon is visible from the Earth. As the days pass, the Moon continues in its orbit around the Sun, but since the light comes from the Sun (not the Earth) the portion of the illuminated Moon which is visible from Earth diminishes.

Half of the Moon is always lit by the Sun. However, at the Third Quarter, only half of the illuminated part is visible from Earth. And day by day, as the Moon continues in its orbit, less and less of the illuminated part is visible. At the new moon, the Moon is between the Earth and the Sun, and only the shadowed part of the Moon is visible. As the Moon continues in its orbit, first a sliver is lit up, then more and more each day until the Moon is full again.

You can demonstrate how this works for yourself. In a dark room, place one bright light at one end. Stand near the other end with your back to the light. Hold a ball, like a beachball or Basketball, at arms length in front of you, but high enough to be out of your shadow. The entire visible surface of the ball is illuminated by the light.

Turn a little to the left, and notice that a fraction of the ball is now in shadow. Continue to turn slowly, and watch the "phases" of the ball. That's how the Moon's phases work.

If the shadow of the ball is on your face, that's what happens in a solar eclipse, and if your shadow falls on the ball, that's how we see a lunar eclipse.

Answer 3

As you probably know, the earth orbits around the sun and the moon orbits around the earth. The moon phases depend on the arrangement of the three bodies.

The sun always lights one half of the moon - the side facing the sun. However, the moon's position with respect to the earth does not always allow us to be able to see the whole lighted side. If the moon is between the earth and the sun, we can't see the lighted side at all. If the moon is on the opposite side from the sun, we can see the whole lighted side. Anywhere in between and we're looking at the lighted side from different angles, meaning we see various amounts of the moon depending on how much of the lit part we can see. Because this goes in a regular cycle, it produces moon phases, or set times when certain amounts of the moon will be seen.

Here's a really good applet to illustrate this:

http://www.ioncmaste.ca/homepage/resources/web_resources/CSA_Astro9/files/multimedia/unit3/phases_moon/phases_moon.swf

Answer 4

It's mainly the changing position of the Moon as it orbits the Earth. (Also there is a smaller effect caused by Earth and Moon orbiting the Sun.)

The Moon's shape appears to change because we see different amounts of the Moon's sunlit hemisphere.

For example, we can see the "Full Moon " only when the Earth is between the Moon and the Sun.

Answer 5

This is caused by the Moon's revolution around Earth.

Answer 6

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