what would happen between the gravitational force of earth and the sun, if...

  • Thread starter Thread starter Solidsnake B
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Solidsnake B

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...the sun was 2x larger? How would this affect the motion of Earth, if its distance to the Sun didn’t change?
 
Plug in the numbers.

This is Kepler's Third Law.

You *could* do the math, but I find this site much easier:
http://www.1728.com/kepler3a.htm

Click thet you want to solve for "time."
Plug in for:
Mass = 1 solar mass
Distance = 1 AU

Hit "calculate"

You should come up with a number very close to one year.

Now, do everything the same, but select 2 solar masses.


Earth needs to orbit a little bit faster to maintain a stable orbit at that distance, huh?
 
When you mention 2x larger, I suppose you mean twice the diameter.

Normally a sphere that is twice a diameter will have eight times the volume and in this case would have eight times the mass and eight times the gravitational pull at a certain distance.

However, a star is a ball of gas and the more mass it has, the more tightly the gravity pulls it inward. For a star to have twice the diameter it would have to have a far larger mass than eight times its present amount. Adding mass reaches a point where more mass actually causes the diameter to shrink!

In any case, increasing the sun's mass would cause the Earth to spiral inward to a closer orbit.
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