### Circular Orbits around the Earth

 Possible Satellite orbits (circular orbits only)     There are 6 satellites shown in "orbit" around the center object (the Earth). The RED one is the geo-synchronous orbit (1 orbit = 24 hours).     You can zoom in or out (the grid lines are in units of 2Re), and you can change the time factor (1 day = x minutes/seconds/etc.).     You can turn on or off the velocity/radius display.     [I'm sorry about the color scheme here - for some reason I can't use any green in the colors of the satellites, or the trails don't work - I'm trying to figure out why.] Show radius/velocity information Time factor for animation : 1 day = 1 seconds in animation 1 day = 10 seconds in animation 1 day = 1 minute in animation Spatial zoom factor for animation : 200 Earth Radii across 20 Earth Radii across 10 Earth Radii across

Description
This animation illustrates satellites around the Earth (pretend you are above the North pole of the Earth, looking down). Of special significance is the location of the Geo-sychronous orbit (that's the orbit that takes 24 hours - thus the satellite will stay at the same point above the Equator -- that's the RED orbit, and notice the line on the Earth that rotates with the 24 hour period). If you zoom out, you will see the Moon's orbit also.
Zooming in, you can see the orbit that would occur right at the Earth's radius (i.e. at the surface of the Earth) ... we really can't orbit a satellite at that location, but Bug Bunny can throw a baseball around the Earth! (He used it to prove that the Earth was round .. and his data? ... Travel stamps when the baseball came back!) [Note : the orbits you are seeing are reasonable approximations of the true orbits ... but if you pick a very short time step (1 second) and zoom in, you will see strange behavior (based on the approximation/graphics that is being used ... trust me, that's not what the satellites do!)

Credits :
Original Physlet problem authored by Wolfgang Christian. Modified extensively by Dr. Scott Schneider