Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
... The orbits of the planets are nearly circular as a result of the
accretion process that formed them. That is the dust in elliptical
orbits is more likely to collide with things since they pass through
the circular orbit material and can collide with other elliptically orbit
dust traveling in different directions as well. By an averaging process
the "preferred material" will be that in circular orbits. The nearly
circular orbiting dust clouds can become concentrated by perturbations
from other clouds in similar orbits and the Poynting-Robertson effect
acting on the dust.
Gary
P.S. Periapse is when the object is closest to the star, i.e. Perihelion
in the case of the sun, perigee for the earth. Today perturbations of
other bodies and tidal effects are the main causes of the changes in
orbital parameters in the solar system.