other than earth. we dont know the density of the planet from earth
2006-10-24 22:28:40 · 4 answers · asked by KANDE RAGHU V 1 in Science & Mathematics ➔ Astronomy & Space
what is the relation between gravity and the density or mass of the planet
2006-10-26 04:21:42 · update #1
By using laws of physics. Two things are required: knowledge of the size of the planet and the planet needs to have a moon (an orbiting or flying by spacecraft or an asteroid coming close will do, as well). By knowing the size of the planet and by measuring the distance and orbital size of its moon you can determine the mass of the planet and, hence, its density. The size of the orbit and its velocity in orbit of any celestial body is determined by the mass of the body about which it orbits (so, a one-pound satellite orbits earth in the same time and at the same velocity as a multi-ton satellite). If you know the size of the orbit and the velocity in that orbit you can determine the mass and density of the central member of the system. I don't know how scientists calculate it using a spacecraft or asteroid that merely flys by, but they need its velocity and the amount the planet disrupts the path of the spacecraft. It isn't all that complicated but involves several steps of calculations using the "universal gravity constant", G, and the radius of the orbit. Almost any high school level or higher physics textbook will show the formulas. I believe an asteroid was first used to determine the size of the solar system when if passed close to one of the planets.
2006-10-25 02:07:07 · answer #1 · answered by David A 5 · 2⤊ 0⤋
Density is just mass divided by volume. Measuring volume is easy if you know the distance. In that case you can just measure the size by looking at it through a telescope. You can know the mass from the orbit of a moon orbiting that planet. For planets without Moons, like Venus, you need an asteroid to pass close to it so you can see how much the path of the asteroid is bent by the gravity of the planet. Since asteroids don't really get close to Venus, we have to rely on very slight effects on the orbits of Earth and Mercury due to the gravity of Venus. Of course, now days, space craft sent to the planet give us a very accurate mass because the space craft is orbiting the planet like a small moon.
2006-10-25 09:15:47 · answer #2 · answered by campbelp2002 7 · 1⤊ 0⤋
By doing the same thing as how we found out earth's mass
2006-10-25 05:57:45 · answer #3 · answered by amanda a 2 · 0⤊ 0⤋
by measuring its gravity
2006-10-25 05:39:24 · answer #4 · answered by genius sonia 3 · 0⤊ 0⤋