also if jupiters moon has about the same mass as the moon and orbits jupiter at about the same distance that the moon orbits the earth (center to center). then why does it take only 1.8 days to orbit jupiter but our moon take 27.3 days to orbit the earth?
2007-01-20 15:49:38 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
another question if a planet orbiting a massive star has the same orbital period as a planet orbiting a low-mass star, wich of the planets orbits at a greater distance from its star?
2007-01-20 18:13:10 · update #1
The key to this question is the mass of the bodies the two moons orbit. The moon you are referring to is Io. Jupiter has 318 times the mass of the earth, with a surface gravity of 21 m/s^2 vs the earth at 9m/s^2. An orbit is basically a point of balance between the two bodies, fast enough that the moon (or smaller body) is not 'sucked' into the larger body, slow enough not to achieve escape velocity and not be there at all. Io must travel faster than our moon in order to remain in its orbit and not get sucked into Jupiter which has a much larger gravitational attraction than earth does.
2007-01-20 16:10:38 · answer #1 · answered by David W 3 · 1⤊ 0⤋
The two previous responders were correct. Just as an add-on, they determine a star's mass on how large it is also. That makes a good estimate if there is no sign of anything orbiting it. Another possible way to estimate its mass is if the star is dying. Because of the fluctuations and oscilations of the size of a dying star, the range of its original mass could easily be determined.
2007-01-21 00:52:31 · answer #2 · answered by thenextchamp919 2 · 0⤊ 0⤋
Hi. David W is correct on your second question. The first requires that the mass of the star be calculated (or approximated) and the period (orbital) of the second body must be known.
2007-01-21 00:34:21 · answer #3 · answered by Cirric 7 · 1⤊ 0⤋