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No. If the Earth's mass were to vanish, the Moon would continue to orbit the Sun. It would be a bit more wobbly, but the Earth is not an essential part of the

by keenerd 15y ago

No. If the Earth's mass were to vanish, the Moon would continue to orbit the Sun. It would be a bit more wobbly, but the Earth is not an essential part of the system. If the same happened to Jupiter, all of those moons would fly out of of the solar system. (Or at least go cometary.) None of the orbits would survive.

joshAg 15y ago
If Jupiter were to orbit the sun at the same distance of the earth, what would happen to the orbits of the moons if its mass suddenly disappeared? Would they still be cometary (at the least) or would they settle into a planetary orbit?
- keenerd 15y ago
  At 1AU, orbital velocity is 42.3 km/s. Io does 17.3 km/s relative to Jupiter. Io would be gone. Calliso does 8.2 km/s and I highly suspect that would be too fast to maintain a planetary orbit at 1AU. The orbital velocity of Earth is the escape velocity of the solar system, from Earth (42.1 km/s). Fun fact, this means that if we ever wanted to dispose of nuclear waste by dumping it in a star, we'd need much less rocket fuel to hit Alpha Centauri than the Sun.
  - joshAg 15y ago
    Jupiter has an orbital velocity of only 13.7 km/s, so even if Io is going the right direction and all the elliptical planes are parallel, isn't that still just a max orbital velocity of ~40 km/s, which is slow enough for orbit at 1AU? It'd be interesting to see what happens at Jupiter's orbit, thouh. Does Io always leave? What about Callisto? It seems like there would be a large part of their orbit that would send them off into cometary orbits (or worse) depending on what direction they are going when scotty beams jupiter aboard the enterprise.
  - whatusername 15y ago
    Can you explain (or link to) "Fun fact, this means that if we ever wanted to dispose of nuclear waste by dumping it in a star, we'd need much less rocket fuel to hit Alpha Centauri than the Sun." It's not making much sense to my tired mind today.
    - gujk 15y ago
      It takes less energy to accelerate an object away from both the Earth and sun (assuming your launch pad is on an appropriate spot on the Earth surface), than to accelerate an object away from the Earth but into the sun without just getting the object stuck in an orbit like Venus or Mercury.
Retric 15y ago
That has to do with the distance between the sun and Jupiter not just Jupiter's mass. http://en.wikipedia.org/wiki/Deimos_%28moon%29 http://en.wikipedia.org/wiki/Deimos_%28moon%29 Deimos would continue to orbit the sun in much the same way that the moon would if it's planet disappeared. (Moon: 1.022 km/s, Deimos: 1.3km/s, Callisto's 8.204 km/s. Earth 29.78 km/s, Mars 24.077 km/s, and Jupiter 13.07 km/s) Edit: http://en.wikipedia.org/wiki/Escape_velocity http://en.wikipedia.org/wiki/Escape_velocity To escape from the suns orbit at Jupiter's distance from the sun takes 18.5 km/s vs Mars orbit's 34.1 km/s, or the Earth's orbit 42.1 km/s. PS: The moon was the original example of 'moon' so it's a moon by definition. Any definition that does not include it must be describing something other than a 'moon'.
- keenerd 15y ago
  Your Deimos (and Moon) velocities are off, as those are velocities relative to Mars and Earth comparatively. The real question is, does 24.1km/s +- 1.3km/s keep Deimos in orbit without Mars. 5% change in velocity will probably knock it a bit out of whack, but I am not doing the perigee/apogee calculations right now. PS, The Earth was the original example of 'flat' and nothing is ever allowed to change as we gain better understanding.
  - Retric 15y ago
    Everything's orbital velocity was taken relative to what they orbit. My point is if you take Jupiter and +/- the moon's orbital velocity you get a more extreme orbits than you do with Mars +/- Deimos. So the new orbits say just as much about how far they are from the sun vs what they orbit. PS: The Earth is not the original definition of flat.
    - keenerd 15y ago
      No, you took the Moon's velocity relative to the Earth. The Moon orbits the Sun and its velocity relative to Earth is only useful for astrology purposes.
      - 15y ago
harshpotatoes 15y ago
I don't see how this and Kepler's laws fit together. The moon's mass is significantly different from the earth. How could the moon have the same orbit as the earth if the earth wasn't there?
- joshAg 15y ago
  the orbit of a satellite does not depend on the mass of the satellite. the period and orbital velocity are dependent on the mass of the orbited object and the radius of the orbit.

by keenerd 15y ago

joshAg 15y ago

If Jupiter were to orbit the sun at the same distance of the earth, what would happen to the orbits of the moons if its mass suddenly disappeared? Would they still be cometary (at the least) or would they settle into a planetary orbit?

keenerd 15y ago
At 1AU, orbital velocity is 42.3 km/s. Io does 17.3 km/s relative to Jupiter. Io would be gone. Calliso does 8.2 km/s and I highly suspect that would be too fast to maintain a planetary orbit at 1AU. The orbital velocity of Earth is the escape velocity of the solar system, from Earth (42.1 km/s). Fun fact, this means that if we ever wanted to dispose of nuclear waste by dumping it in a star, we'd need much less rocket fuel to hit Alpha Centauri than the Sun.
- joshAg 15y ago
  Jupiter has an orbital velocity of only 13.7 km/s, so even if Io is going the right direction and all the elliptical planes are parallel, isn't that still just a max orbital velocity of ~40 km/s, which is slow enough for orbit at 1AU? It'd be interesting to see what happens at Jupiter's orbit, thouh. Does Io always leave? What about Callisto? It seems like there would be a large part of their orbit that would send them off into cometary orbits (or worse) depending on what direction they are going when scotty beams jupiter aboard the enterprise.
- whatusername 15y ago
  Can you explain (or link to) "Fun fact, this means that if we ever wanted to dispose of nuclear waste by dumping it in a star, we'd need much less rocket fuel to hit Alpha Centauri than the Sun." It's not making much sense to my tired mind today.
  - gujk 15y ago
    It takes less energy to accelerate an object away from both the Earth and sun (assuming your launch pad is on an appropriate spot on the Earth surface), than to accelerate an object away from the Earth but into the sun without just getting the object stuck in an orbit like Venus or Mercury.

Retric 15y ago

That has to do with the distance between the sun and Jupiter not just Jupiter's mass. http://en.wikipedia.org/wiki/Deimos_%28moon%29 http://en.wikipedia.org/wiki/Deimos_%28moon%29 Deimos would continue to orbit the sun in much the same way that the moon would if it's planet disappeared. (Moon: 1.022 km/s, Deimos: 1.3km/s, Callisto's 8.204 km/s. Earth 29.78 km/s, Mars 24.077 km/s, and Jupiter 13.07 km/s) Edit: http://en.wikipedia.org/wiki/Escape_velocity http://en.wikipedia.org/wiki/Escape_velocity To escape from the suns orbit at Jupiter's distance from the sun takes 18.5 km/s vs Mars orbit's 34.1 km/s, or the Earth's orbit 42.1 km/s. PS: The moon was the original example of 'moon' so it's a moon by definition. Any definition that does not include it must be describing something other than a 'moon'.

keenerd 15y ago
Your Deimos (and Moon) velocities are off, as those are velocities relative to Mars and Earth comparatively. The real question is, does 24.1km/s +- 1.3km/s keep Deimos in orbit without Mars. 5% change in velocity will probably knock it a bit out of whack, but I am not doing the perigee/apogee calculations right now. PS, The Earth was the original example of 'flat' and nothing is ever allowed to change as we gain better understanding.
- Retric 15y ago
  Everything's orbital velocity was taken relative to what they orbit. My point is if you take Jupiter and +/- the moon's orbital velocity you get a more extreme orbits than you do with Mars +/- Deimos. So the new orbits say just as much about how far they are from the sun vs what they orbit. PS: The Earth is not the original definition of flat.
  - keenerd 15y ago
    No, you took the Moon's velocity relative to the Earth. The Moon orbits the Sun and its velocity relative to Earth is only useful for astrology purposes.
    - 15y ago

harshpotatoes 15y ago

I don't see how this and Kepler's laws fit together. The moon's mass is significantly different from the earth. How could the moon have the same orbit as the earth if the earth wasn't there?

joshAg 15y ago
the orbit of a satellite does not depend on the mass of the satellite. the period and orbital velocity are dependent on the mass of the orbited object and the radius of the orbit.