- #1
SF
Found this in another forum:
1) Is the moon really orbiting the earth?
2) What is the effect of the Universe's expansion on the Moon/Earth or Sun/Earth distance?
http://www.news.cornell.edu/stories/March06/CMB_Timeline300.jpg
From that image, there's been about 10-20% universe expansion during the last 4 billion years.
Does that translate into any effect on the "small" distances in our Solar System?
Thanks.
1) Is the moon really orbiting the earth?
The sun already has greater gravitational effect (stronger force) on the moon than the Earth does. (If you do not believe, calculated the relative Mass/separations^2 ratios for both sun and Earth (except for factor "G", the gravitational force at the moon).
In fact, the moon is now going arround the sun in essentially the same elliptic orbit as the Earth is. I.e. The moon only appears to be going around the Earth when viewed from the Earth. In fact, it is always with a trajectory that is curving towards the sun. Never is the moon on a trajectory that is convex towards the sun (as you would expect it to be if it were going around the Earth like most man made satellites are).
If the Earth were magically removed there would be very little difference in the moon's orbit about the sun. That orbit now has slight
"wobbles" about the true ellipse, which are caused by the relatively weak gravity from Earth and of course if Earth disappeared or had no gravity, they would cease to exist, but viewed from Mars, it would not be a noticable change in the moons orbit if the Earth had zero gravity. Earth does NOT control the moon. Really Earth does not have a natural moon, but is the larger of two interacting masses that co-orbit the sun.
Thread is badly named, reflecting this common erroneous POV. Should be called "Sun's planatoid near Earth" or something like that.
2) What is the effect of the Universe's expansion on the Moon/Earth or Sun/Earth distance?
http://www.news.cornell.edu/stories/March06/CMB_Timeline300.jpg
From that image, there's been about 10-20% universe expansion during the last 4 billion years.
Does that translate into any effect on the "small" distances in our Solar System?
Thanks.
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