What causes the apparent repeated changes of the moon shape?

Answer 1

The Moon doesn't change shape. It's only our view of the sunlit part that changes. The amount of the sunlit part that we see determines the "shape" of the Moon, as we see it.

The Moon orbits the Earth every 27.3 days or so. During this orbit, only one half of the Moon faces the Sun, at any particular time.

The Moon rotates just once during each orbit of Earth, thus keeping the same side facing us.

So the side that faces the Sun slowly changes as the Moon orbits the Earth.

So, as the Moon orbits us, we see different amounts of the Moon lit up, going from a very thin sliver, to a crescent, to half, then to full and back again.

These are called the Moon's "phases".

It actually takes about 29.5 days for the Moon to go through all its different phases. That's because the Moon (along with the Earth) is orbiting the Sun, as well as going around the Earth.

Answer 2

It doesn't. The sun just reflects off of it and we see different parts of the illuminated surface at different times.

The moon remains spherical (roughly).

Observers on Earth see different parts illuminated by the Sun during the Moon's orbit around the Earth.

When opposite from the Sun the moon appears full (all of the illuminated surface is visible to Earth observers (if exactly opposite so it comes in the Earth shadow there will be a lunar eclipse for a few hours).

Answer 3

It hasn't, that's why Astronomers are able to use the moon as a reference to gauge the age of the earth and how violent of a solar system we really have.

If your meaning Size , then it is simply because the moon is an elliptical orbit and the Moon will get smaller and larger depending on where it is in the cycle.

Or if your meaning the crescent shape the moon cycles through , it is because the side of the moon reflecting the sun is in a different position every day. A New moon means that it is reflecting no light from the sun back to the earth and a full moon means it has a full face of light reflecting back to earth. the same goes for the other phases of the moon.

Hope this was helpful.

The moon rotates, and there's a dark side of the moon, and a light side of the moon. Every night, we see a different part of a side. It is not the actual shape of the moon that changes, but what part we can see.

Answer 4

As strange as it may sound, during the course of one lunar cycle we are observing one lunar day as it unfolds on the moon's surface. This is because the moon's orbit around the earth is 'tidally locked' with the earth, so one lunar cycle (all the moon phases) is equal to one rotation of the moon relative to the sun. The night time parts of the moon sometimes make the moon appear to have an odd shape. The moon is still all there and it is basically spherical, but the unlit parts of the moon may be obscured by earth's daylight, clouds or other things in our own atmosphere. The ordinary phase appearance of the moon during a typical month has nothing to do with eclipses or with the earth's shadow. As mentioned above, it is the natural nighttime shadow of the moon that we are observing. Often, when you observe a crescent moon, you may dimly see the rest of the moon's body giving back light reflected from the earth's sunlit surface I GUESS.

Answer 5

because of the position of the sun.
It doesn't change shape. It appears to change because as it turns the parts on which the sun shines change. You only see the bits lit by the sun. The rest is so dark it merges with the sky.

Answer 6

The moon lookes like it is changing shape but it is always a sphere, we only see a 2D shape from earth though. The moon changes due to the light from the suns angle because everyday the moon rotates around earth, and every night the moon will be in a different angle compared to the sun so the light is shaded in some areas f the moon ( i ramble on too much) I hope that makes sense, it makes better sense in my head!

Answer 7

It doesn't; it just looks like it because the proportion of the visible half of the Moon that is illuminated by the Sun varies day by day throughout the month. It's just a trick of perspective; we're here, the Sun is THERE, and the Moon is over THAT way.

Answer 8

It only appears to change. It's because the sun sends light to the moon and the moon absorbs some, and reflects some. The light we see on the moon is the light the moon has reflected from the sun.

Answer 9

Because the moon does not produce it's own light, since the moon orbits the Earth, we only see the sunlit side of the moon. The "shape" of the moon depends on where the moon is positioned in relation to the Earth and sun. When the moon is between the sun and the Earth, the side of the moon facing us is in complete darkness (we call this the New Moon), whereas when the Earth is between the moon and the sun, the side of the moon facing us it fully in sunlight, we call this the Full Moon.

Answer 10

The moon appears to change shape due to the shadow of Earth. Depending on what our planet's location is in between the moon and the sun determines what shape will appear. Since Earth moves at a steady and predictable pace, we know what the moon will look like from night to night.