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Apparent equality between Jovian esc. velocities and Sol's esc. vel.
Okay, I've never heard anything about this before=E2=80=A6Somebody =
please explain this: In scanning the wikipedia entry on "Escape Velocity", at https://en.wikipedia.org/wiki/Escape_velocity , I noticed in its list of escape velocities that for the Jovian planets alone (but not for smaller planets) the tabulated escape velocities for each Jovian was almost exactly identical to the escape velocity for the sun itself AT that planet's orbit. IE: (1) Jupiter's esc. vel. = 60.2 km/s Sol's esc. vel. = at J's orbit = 60.4 km/s (2) Saturn's esc. vel. = 36.09 km Sol's esc. vel. a= t S's orbit = 36.3 km/s (3) Uranus's esc. vel. = 21.38 km/s Sol's esc. vel. = at U's orbit = 23.7 km/s (4) Neptune's esc. vel. = 23.56 km/s Sol's esc. vel. = at N's orbit = 23.7 km/s i.e.: Sol/planet ratios very close to unity. On the other hand, the analogous values for the smaller terrestrial planets are in a ~Sol/planet ratio very roughly equal to ~1.5 to ~2 or so Am I the victim of a vast astronomical hoax, or just some blitheringly obvious well known phenomenon, or can I get a door prize at the Nobel's shindig next year? :-) [[Mod. note -- You're very likely just seeing approximate coincidences. If I've done my algebra correctly the escape velocity at a distance r from a mass M is given by sqrt(2GM/r) where G is the Newtonian gravitational constant, so you're essentially asking where there's any special relationship between the ratios M_sun / planet_orbit_radius_about_sun and M_planet / planet_radius There no reason to expect any such relationship, since these ratios are set by quite different physical phenomena, and the first ratio may change over time if the planet migrates in the solar disk during the early formation of the solar system. -- jt]] |
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