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Outer Solar System Viewer
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Seven bodies are depicted here. The Sun (yellow) is at the center of the diagram, and the gaseous planets Jupiter (orange), Saturn (orange), Uranus (light blue), and Neptune (dark blue) follow nearly circular orbits around the Sun. Pluto (gray), however, has a highly elliptical orbit. During the 1980's and 1990's Pluto was closer to the Sun than Neptune. You can change the orbit of the seventh object, a comet (red, connected to Sun by yellow line), with the sliders underneath the diagram.

  • The Semimajor Axis, a, is measured in units of Astronomical Units (AU). One AU is the distance from the Earth to the Sun.
  • The orbial Eccentricity, e, is unitless. This parameter is a measure of the roundness of the orbit and can take on any positive value.
  • The Longitude of pericenter, w (omega), is an angle with units of degrees. Omega is measured from a reference direction, here the positive x-axis (green line at 3 o'clock), to pericenter (the closest approach of the orbit to the Sun).
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    Created on Nov 22, 1998.