neptune is the eighth planet from the sun (in order of increasing mean distance or semimajor axis).
neptune is the eighth planet from the sun (in order of increasing mean distance or semimajor axis).
which is the eighth planet from the sun (in order of increasing mean distance or semimajor axis)?
neptune
eighth planet (disambiguation)









































eighth planet may refer to:









































bullet::::- neptune, the eighth planet from the sun









































bullet::::- ceres (dwarf planet), the eighth object to be identified as a planet









































bullet::::- pluto, considered a planet from 1930–2006, was closer to the sun than neptune from 1979–1999, during which it may have been considered the eighth planet and neptune the ninth planet









































section::::see also.









































bullet::::- first planet (disambiguation)









































bullet::::- second planet (disambiguation)









































bullet::::- third planet (disambiguation)









































bullet::::- fourth planet (disambiguation)









































bullet::::- fifth planet (disambiguation)









































bullet::::- sixth planet (disambiguation)









































bullet::::- seventh planet (disambiguation)









































bullet::::- ninth planet (disambiguation)









































bullet::::- tenth planet (disambiguation)
eighth planet (disambiguation)
note that formula_16 in the above equation, is the time for the mass to fall in a highly eccentric orbit, make a "hairpin" turn at the central mass at nearly zero radius distance, and then returns to r when it repeats the very sharp turn. this orbit corresponds to nearly linear motion back and from distance r to distance 0. as noted above, this orbit has only half as long a semimajor axis (r/2) as a circular orbit with radius r (where the semimajor axis is r), and thus the period for the shorter high-eccentricity "orbit" is that for one with an axis of r/2 and a total orbital pathlength of only twice the infall distance. thus, by kepler's third law, with half the semimajor axis radius it thus takes only (1/2) = (1/8) as long a time period, as the "corresponding" circular orbit that has a constant radius the same as the maximal radius of the eccentric orbit (which goes to essentially zero radius from the primary at its other extreme).
free-fall time