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Understanding satellite orbits

  1. Jun 14, 2009 #1
    This is nothing so involved as the actual mechanics of orbit. I'm just curious, is there a preferred plane that satellites orbit in? I ask because on my frequent stargazings, after my eyes are VERY well adjusted to the dark, I can see what I assume to be satellites moving pretty quickly across the sky. Some of them are very faint, and I can only track them by keeping them in that "sweet spot" in my vision slightly off of directly looking at them.

    The paths they take are mostly north-west. My question stems from the fact that some of them have paths that are at angles to this, such as north-east at about 30 degrees between the two.
  2. jcsd
  3. Jun 15, 2009 #2


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    Staff: Mentor

    There is no single preferred plane, but there may be any number of specific reasons for the plane of a particular satellite:

    -The plane intersected the Kennedy Space Center (or another launch site) and the center of the earth at the time of the launch.
    -The plane is at the equator (for geostationary satellites).
    -The planes of constellations of multiple satellites intersect in ways that provide the best global coverage.
    -The plane intersects the poles (for satellites requiring a polar orbit).

    I'm sure there are many other reasons for chosing a plane. Most satellites will, however, travel from west to east due to the rotation of the earth being used to assist their launch. And since the Kennedy space center is at 30 degrees north latitude, that's the minimum inclination for a launch that doesn't require a course correction. Ie, if a launch is made due east from the Kennedy space center and follows a circular path, it will oscillate betwen 30 degrees north and 30 degrees south latitude.
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