On October 17th, 2007 Anonymous (not verified) says:
Found this browsing for a paper on Gliese 581 star system. Just have to comment that your knowledge of the nature of gravity is indeed shaky, even though it's about three months late. Formula for gravity is as follows:
F = (G*m1*m2)/r^2
F is the force exerted by gravity, G is the gravitational constant of the universe, m1 is the mass of the planet, m2 is the mass of the body on which the force is being exerted, and r is the distance between the two objects. Gravity of a planet is calculated as if the entire force were centered at an infinitesimal point in the center of the planet, i.e. r here should be the radius of the planet.
Therefore a planet with a mass 15 times that of Earth would only have a gravity 15 times that of Earth if the radius of the planet were equal to the radius of Earth.
If 581d's radius is 3.9 times the radius of Earth, the gravity would be equal to that of Earth.
Found this browsing for a
Found this browsing for a paper on Gliese 581 star system. Just have to comment that your knowledge of the nature of gravity is indeed shaky, even though it's about three months late. Formula for gravity is as follows:
F = (G*m1*m2)/r^2
F is the force exerted by gravity, G is the gravitational constant of the universe, m1 is the mass of the planet, m2 is the mass of the body on which the force is being exerted, and r is the distance between the two objects. Gravity of a planet is calculated as if the entire force were centered at an infinitesimal point in the center of the planet, i.e. r here should be the radius of the planet.
Therefore a planet with a mass 15 times that of Earth would only have a gravity 15 times that of Earth if the radius of the planet were equal to the radius of Earth.
If 581d's radius is 3.9 times the radius of Earth, the gravity would be equal to that of Earth.