When we can only see half of the Moon, where is the rest of it? 


4 Answers

Samuel Chiltern Profile
Samuel Chiltern answered
The Moon never goes anywhere at all, but when it is anything other than fully-illuminated by sunlight, it appears that at least a small part of it is missing.

This can be explained by the way in which the relative positions of the Sun, Earth and Moon change over time, which is called the lunar phase.

The Phases of the Moon (Lunar Phase)
The apparent fluctuation in the shape of the Moon is caused by our viewpoint on the Moon from Earth. The actual shape of the Moon has nothing to do with it, and the Earth doesn't cast a shadow upon it either.

A full moon occurs when the Moon is on the opposite side of the Earth from the Sun. A new moon (completely black) occurs when it is between the Sun and the Earth, because naturally, the side that we see at this point is not illuminated by the Sun at all.

From our viewpoint on Earth, we can never see slightly more than half of the Moon's surface in total. The Moon's rotation has been slowed down by tidal forces on Earth, which has synchronised its axial rotation with its orbit of the Earth. This is known as tidal locking.

The Far Side of the Moon
The far side of the Moon is mostly not visible from Earth, therefore, no matter what phase it happens to be in at the time. Approximately 59% of the Moon's surface can be viewed over time, owing to an effect known as libration, which is basically a kind of 'wobbling' of the Moon in the night sky.

The Dark Side of the Moon
Not to be confused with the far side of the Moon, the dark side is the part that faces the Earth, but which is not currently illuminated by sunlight. The near side and the dark are exposed to roughly the same amounts of sunlight on average, but we can only see the illuminated part that is visible from our viewpoint on Earth.
Anonymous Profile
Anonymous answered
Behind the lit part. The moon is casting its own shadow. The bright part is pointing toward the position of the sun.
Tolo Tolo Profile
Tolo Tolo answered
It's the angle at which the Earth is tilted at that point in time. When you face to the East, you can only see a fraction of the West or the South, as compared to when you are facing West or South.
Mulford Samper Profile
Mulford Samper answered
The Moon is actually round, the half that's lit is facing the Sun, while the other half is facing space.

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