| famousringo said: Can somebody explain to me how this planet could have six times the Earth's mass and yet less gravity? Is it a matter of density and how far into the atmosphere you have to travel before you reach the surface? Edit: Maybe they're figuring in displacement as if you didn't have to visit the planet inside a sturdy pressure hull? |
The accleration you experience caused by an object equals GM/r^2 where G is a constant, M is the objects mass, and r is the distance between you and it. When you put in Earth's mass and radius, you get 9.81 m/s^2 (or 1g). When you put in 6.55 times the mass of the earth and 2.678 times the radius of the earth, you get 8.96 m/s^2 (or .913 g). You can try it yourself.
More plainly, distance (radius) plays a larger role in the gravity than mass because it's squared, as opposed to just being to the first power like mass.
Edit: So, even though mass is 6.55 times bigger and the radius is only 2.678 times as big, the increased radius has a larger effect because it's squared in the equation (2.678 squared is 7.17).
