Holy Feck I Feel Stupid.....

[phiphika1453]

Who in the hell knew that the phases of the moon weren't caused by Earth's shadow?

Also the moon spins on its own axis at the exact rate it takes to orbit the earth (27.3 days), this is why we always see the same face of the moon.

Please be honest and tell me I am NOT the only person who did not know this until today.

Detailed Description of Moon Phases

[doucy]

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Also the moon spins on its own axis at the exact rate it takes to orbit the earth (27.3 days), this is why we always see the same face of the moon.


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I did not know this

[Phil153]

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Who in the hell knew that the phases of the moon weren't caused by Earth's shadow?

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I think everyone knows that.

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Also the moon spins on its own axis at the exact rate it takes to orbit the earth (27.3 days), this is why we always see the same face of the moon.

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I learnt this in a sophomore meteorology class, and wasn't the only surprised. But it's obvious if you ever stop and think about it.

[PairTheBoard]

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Also the moon spins on its own axis at the exact rate it takes to orbit the earth (27.3 days), this is why we always see the same face of the moon.


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I did not know this

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I knew it but I had forgotten about it. Evidently some others around here did as well. The information would have been relevant to the question in a recent thread about how the temperature of the Earth's surface would behave if there were no atmoshphere. Someone suggested it would vary between night and day the same way the Moon does. I don't think anybody mentioned the relevant fact that the Moon rotates on its axis so much more slowly than the Earth. While a point on the Earth would be exposed to the Sun for about 12 hours in one Earth day, a point on the Moon would be exposed to the Sun for about 14 days in one Moon Day.

PairTheBoard

[Cumulonimbus]

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DID YOU KNOW THAT...

the phases of the moon weren't caused by Earth's shadow?

Also the moon spins on its own axis at the exact rate it takes to orbit the earth (27.3 days), this is why we always see the same face of the moon.

NOW YOU KNOW





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BNYP

[gull]

Yeah, it's not a lunar eclipse. It's us only seeing a portion of the lit side.

[reb]

Of course we only see one face of the moon, otherwise we would see the secret alien bases on the other side..duh [img]/images/graemlins/blush.gif[/img]

[Fels krone]

I learned this from AFN informercials

[HP]

what's even cooler is if you wait long enough, the length of Earth's day will lengthen to a year*

Just as for the moon, is has to do with tidal forces IIRC

*I'm not sure if the Sun will expand and incinerate Earth beforehand though

[evank15]

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I learnt this in a sophomore meteorology class, and wasn't the only surprised. But it's obvious if you ever stop and think about it.

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It isn't obvious at all.

It is caused by a mechanism called tidal locking, where the time for a body to become tidally locked to another is a function of a lot of things, including (i'll probably miss a couple) the masses, the semi major axis, the radii of the bodies; the moment of inertia, density, rigidity and surface gravity of the satellite.

There are also harmonic tidal locks, such as Mercury around the Sun, which is tidally locked in a 3:2 resonance.