PDA

View Full Version : Will the sun as a red giant affect it's gravity?



Tritons Inquiry
2016-Oct-22, 10:31 PM
Assuming the sun doesn't lose any mass in the prosses, will the sun's gravity change when it becomes less dense and larger? (as a red giant for example):confused:

StupendousMan
2016-Oct-22, 10:51 PM
Short answer: no.

DaveC426913
2016-Oct-22, 11:06 PM
Longer answer:
Depends on where you are. If you're still on Earth when the sun expands out to Mars, the Sun's pull will be partly negated - since you wil be inside it - due to Newton's shell theorem.

But otherwsie - if the mass don't change the gravity don't change.

cjameshuff
2016-Oct-23, 12:29 AM
Note that the surface gravity will drop. The gravity at any given distance from the center will remain the same, but the surface will move to a greater distance as the sun expands. (Another example: the surface gravity of Mars and Mercury is almost identical, despite Mars being twice as massive. Mars has a gravity well twice as deep, but due to its higher density and smaller radius, the surface of Mercury is relatively deep in its gravity well. And the "surface" gravities of Saturn, Uranus, and Neptune are similar to that of Earth despite their much greater mass, due to their much lower density.)

publiusr
2016-Oct-29, 05:33 PM
As the sun bloats over time, simple drag may slow the inner planets some