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Old 11-14-2012, 08:39 AM   #52
vive le beau jeu !
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Quote:
Originally Posted by mib View Post
I was just pointing out that while nearly everyone knows that the seasons are switched between the hemispheres, the actual physical explanation of that is not that trivial.

For instance, why does the axis of the rotation not change with respect to the orbital plane? I think this is a result of some gyroscopic effect, but I am not sure.

Take the Moon, for example. It is phase-locked with the Earth -- we never see "the dark side" (it is not really always dark, of course). Why does not the same thing happen with the Earth with respect to the sun?
Quote:
Originally Posted by Monsieur_DeLarge View Post
Tidal locking is a consequence of distance, the bodies' masses, and time. Although the moon is much smaller than the sun, its closer proximity means it exerts a greater tidal influence overall (about 2.5x greater, as far as I remember), so the moon has been locked to the earth first.


Regards,
MDL
Mr.DL explained it well.

you've got a kinda intermediary example with mercury, which is not tidally locked with the sun, but has instead a 3:2 spin-orbit resonance with the sun (rotates 3 times around its axis while making 2 revolutions around the sun... the mercurial day being longer than the mercurial year).



another interesting example is pluto-charon which are always "face-to-face" (both tidally locked to each other).

but i'm afraid that might be a bit too much of information in a short time for the OP...
Quote:
Originally Posted by Desertman View Post
The Earth actually goes round the Sun

The axial tilt of the Earth is fixed at around 23 degrees and has a far greater contribution to the seasons than does the variation in the Earth's orbit around the Sun.
another funny thing in the flat earth stuff is what they say about satellites:
Quote:
"Despite the fact that in October 1957 the Soviet Union launched Sputnik, the world's first artificial satellite, Shenton proved a popular speaker to small groups, enjoying particularly talking to children, never declining an invitation. He claimed that satellites simply circled over a flat disc-world: "Would sailing round the Isle of Wight prove that it were spherical?", he demanded."
from: http://theflatearthsociety.org/wiki/...Samuel_Shenton

now if someone still has this "not sure if serious" picture...
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