Lunation

Comments and questions about the APOD on the main view screen.
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orin stepanek
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Lunation

Post by orin stepanek » Mon Nov 14, 2005 2:40 am

The Moon wobbles once an orbit; the Earth also wobbles once an orbit. Is this phenomenon the norm or is it relatively rare? I mean do other planets and their moons have this wobble?
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Post by ta152h0 » Wed Nov 16, 2005 9:47 pm

I also wobble aslbeit at a higher frequency :D
There was a story on the History Channerl that discussed the link between the pyraminds and astronomy and the alignment of a long hole coincided with the predicted position of a star 13000 years ago ( implying the earth wobbled once every 26000 years. Pass the ice cold one, I earned it :D
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Re: lunation

Post by S. Bilderback » Wed Nov 16, 2005 11:18 pm

ta152h0 wrote: There was a story on the History Channerl that discussed the link between the pyraminds and astronomy and the alignment of a long hole coincided with the predicted position of a star 13000 years ago ( implying the earth wobbled once every 26000 years). Pass the ice cold one, I earned it :D
Pass the cold LaBatt Blue is right. The 26,000 cycle of the northern axis pointing away from the Sun at perihelion to Aphelion and back again is the largest factor in the Earth’s Ice Age cycle (that, ya know, kina buries Canada under 2 kilometers of snow ah).

Go Stars! :D

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orin stepanek
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Post by orin stepanek » Thu Nov 17, 2005 1:13 am

That's very interesting; but I was asking about the wobble that causes the changes in seasons; and whether of not all planets and or asteroids and satellites were also affected in this way. Is this a natural phenomenon or is it unique to the Earth and the Moon???
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Post by ta152h0 » Thu Nov 17, 2005 1:20 am

The wobble you refer to that causes seasonal changes are due to the geometry of the solar system, where the earth's orbit is tilted and follows an ellipse wjere the beast moves closer and further away from the sun every year, coupled with the tilt of the Earth. It is a perception of what we actually see, not what actually happens. It is a great geometry lesson.
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orin stepanek
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Post by orin stepanek » Thu Nov 17, 2005 1:28 am

OK. Makes sense. I guess I forgot some of my high schooling. Thanks!
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Post by S. Bilderback » Thu Nov 17, 2005 1:41 am

orin stepanek wrote:I was asking about the wobble that causes the changes in seasons; and whether of not all planets and or asteroids and satellites were also affected in this way. Is this a natural phenomenon or is it unique to the Earth and the Moon???
The "Wobble" isn't really a factor in the seasonal effects of Earth, The "Wobble" of the Moon is caused by the orbit of the Moon not being fixed directly over the equator, so the observed tilt of the Moon changes in respect to its orbital latitude over the Earth. The orbit of the Moon has about a 10 degree inclination in relation to the Equator, most other naturally orbiting bodies stay with in 1 or 2 degree of the host object's rotation, so in this respect it probably quite rare.

As for the seasonal effect, Mars has nearly the same tilt as Earth, so its probably very common. Now Neptune, it's tilt of 47 degrees would not be so common.

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Post by Empeda2 » Thu Nov 17, 2005 9:39 am

S. Bilderback wrote:The orbit of the Moon has about a 10 degree inclination in relation to the Equator, most other naturally orbiting bodies stay with in 1 or 2 degree of the host object's rotation, so in this respect it probably quite rare.
Is this partly why they believe that the moon may once have been part of the earth?
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Post by S. Bilderback » Thu Nov 17, 2005 12:30 pm

You are absolutly correct my friend! :D

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Post by FieryIce » Thu Nov 17, 2005 2:11 pm

ta152h0, the moons orbit is circular not elliptical, with an eccentricity of .055, quote “the main effect of the eccentricity of the moon's orbit is that the moon will periodically be 6.3° ahead or behind of where it is expected to be. This changes the times of moonrise and moonset by about 25 minutes.”

Image

The Standard Elliptical Orbit, Diagram of Lunar Orbit

Image

Indiana Edu

Our solar system if viewed from top down is circular.
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Post by S. Bilderback » Thu Nov 17, 2005 10:30 pm

6.3 or 10 degrees, unless I'm on my way for a luner landing, it's close enough for me. :wink:

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Post by ta152h0 » Fri Nov 18, 2005 1:50 am

quote - <<<Our solar system if viewed from top down is circular.>>>

That is not true. Our solar system includer Pluto which has a highly excentric orbit. We don't have proof the Kuiper belt is circular. Nature abhors perfect geometry. The original post questioned the weather patterns and the moon is devoid of weather and all my previous words ignored the uniqueness of the moon. We live in a soalr systen that can only support life within the one million mile wide band orbit the earth resides, at least for being of my kind that enjoy a cold one on occasion.
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Post by S. Bilderback » Fri Nov 18, 2005 3:19 am

If the aphelion of all orbiting object are compiled and plotted over millions of years, the solar system is circular – just another definition.

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Post by orin stepanek » Fri Nov 18, 2005 3:33 am

If the moon was once part of the Earth; than I'd say the Earth got the better part of the split.
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Post by Empeda2 » Fri Nov 18, 2005 12:36 pm

You reckon? To quote D. Adams:

About 13 Billion years ago the universe was created suddenly in a big bang. This made a lot of people very angry and is wildly regarded as a bad move.....

:lol:
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