Why does the illumination of the Moon's surface appear to change when viewed from earth even though the sun continuously illuminates half of the moon?

Answer 1

The Moon (and the Earth, and all the other planets) are spherical, ball-shaped. There is only one Sun. So light streams outward from the Sun, and hits the Moon, and the Earth, and all the other planets, asteroids, moons, comets, rocks.... and everything else.

The point is that in this solar system there is only one Sun, one star - and the light comes from one direction. Only half of the Moon can be illuminated. (Actually, at the new moon, the ENTIRE Moon is lit up - half by the Sun, and the other half by reflected "earthshine" from the full Earth!)

Answer 2

Yes, but it is not always the same half. One complete day/night cycle on the moon

is 29.531 days on earth.

Any spot on the moon has the sun up in its sky and light for 14.7 Earth days,

followed by the sun down and not in the sky and darkness for the next 14.7

Earth days. The notable exception to this is, of course, craters at the lunar poles, the bottoms of which remain in perpetual shadow.

Answer 3

When you say "fully lit", remember that you're only looking at 1/2 of the moon's surface.

It's not possible for you to see more than 1/2 of the surface of a ball at any one time.

Try this . . .

Take a flashlight and a tennis ball into a dark room. Close the door

1). Notice that you cannot see the ball.

2). Turn on the flashlight and shine it at the ball.

3). Notice that the front half of the ball is lit up and the back half of the ball is in shadow.

4). Look at the side of the ball. Notice that what you see is 1/2 lit up and 1/2 in shadow.

5). Now think of the moon as a tennis ball, think of the sun as a flashlight, and think about

everything that you have just seen in the dark room.

Answer 4

Yes, half of the moon is always facing the sun. We only see different phases because of the angle at which we view it throughout every month.

.

EXCEPT DURING A LUNAR ECLIPSE!

Answer 5

Yes, how much of the moon we see lit up depends on the position of the moon compared to the sun.

When there is a new moon, although it appears that the moon is not lit up at all, the side of the moon facing away from earth is lit up.

Answer 6

At any moment, 50% of the moon is lit by the sun. But because the moon moves in a nearly-circular path around the earth, the amount of the lit-half that is visible from earth changes throughout the month.

When the moon is "in front" of earth, in the direction of the sun, we are looking up at the dark side of the moon, and we see none of it.

When the moon is "behind" the earth, in the opposite direction from the sun, we look up at the entire illuminated side of the moon, and we see a full disk.

With the moon in other positions, the portion of the lit-half that we can see is more or less, and the shape we see is somewhere in between nothing and a full disk.

Answer 7

Yes (except during a lunar eclipse.

Answer 8

No