This is why humans don't live on the moon.

Classical Mechanics Level 2

From the Earth's point of view, we always see the same side of the moon, which indicates that the moon doesn't rotate at all (relative to our position).

The moon takes 29.5 days to revolve around the Earth. The Earth takes 365.25 days to rotate around the Sun.

We say that a day is the amount of time it takes for a celestial object to rotate on it's axis. In the case of Earth (relative to the sun), it indicates how long it takes the Sun to 'rise again'.

How long is a day on the moon?

1) 1 Earth day
2) 29.5 Earth days
3) 365.25 Earth days
4) The moon doesn't rotate. A day is forever.

4 1 3 2

Chung Kevin by Chung Kevin , 45, Australia

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6 solutions

"From the Earth's point of view, we always see the same side of the moon, which indicates that the moon doesn't rotate at all (relative to our position)." It indicates that the moon takes the same time to rotate on it's axis as it takes to rotate around the Earth.

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John M.
Jan 21, 2014

Since the Moon won't rotate to our vision, then it means that one side of the Moon is ALWAYS facing the Earth.

Keeping that in mind, we know the Moon has to rotate since it does move around the Earth and it is always facing us.

So, the Moon will make one full orbital spin when it fully rotates around the Earth. (Take a simple model, where the Moon makes a perfect 2D circle around the Earth: The moon starts at point a, faces point b, spins around the Earth while always facing it, makes one full circle around the Earth, ends up at point a, faces point b.)

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A good way to think of it is to make a moon with your two fingers, and draw a circle in air while always having the two fingers aligned so that they're "facing" some point in that circle. As you'll see, the fingers make a full rotation once they've made a full circle around that center point, which for moon, is the Earth.

John M. - 7 years, 4 months ago

Relative to the fixed stars on the celestial sphere, the Moon takes 27 Earth days, 7 hours, 43 minutes, and 12 seconds to complete one orbit; however, since the Earth–Moon system advances around the Sun at the same time, the Moon must travel further to return to the same phase.

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Yogesh Ghadge
Feb 25, 2014

the reason is that if we see the table of moon the moon takes 29.5 days to become a full moon day

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Anant Kumar Singh
Jan 31, 2014

the moon rotates on its axis in same no. of days as it take to revolve around earth that is29.5 earth days...

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Moon is bound to earth by a phenomenon called Tidal locking. due to this phenomenon, moon takes exactly the same time to rotate about its own axis as it takes to revolve around the earth. that means, a day in moon in terms of earth days is the time it takes to revolve around earth, that is 29.5 days.

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Abd Ullah - 7 years, 3 months ago

v see one side of moon bcoz it spiniclockwises clokwise n earth spins anticlkwise

zalmey khan - 7 years, 3 months ago

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