How to get orbit's apogee and perigee
How to get orbit's apogee and perigee
I have searched this forum for information about how to get/pin down the locations of apogee and perigee from a comet's orbit and then display their values, but have not find any way that is helpful. Does it need script code or any means else to do so? I am helping on a student project that is to visualise comets orbits and the suitable time for observing their positions near the earth, so the data of apogee and perigee points is needed. Any help is grateful.
Joe
Re: How to get orbit's apogee and perigee
Celestia doesn't display those values directly. However, Celestia can display the distance from the viewpoint to a specified object. So one can determine those values by setting Celestia's time to the time of either aphelion or perihelion, placing the viewpoint at the center of the sun, and Selecting the comet.
The orbital parameters which Celestia uses and which you can easily see are those in whatever .SSC catalog is used to define the orbit of the comet that you're interested in. Given those parameters, one could write a Lua (Celx) script to calculate the aphelion and perihelion of a comet. I don't think anyone has written one yet to do that, though.
Note: Apogee and perigee are the distances from the center of the Earth to an object orbiting around the Earth. The suffix helion is used for objects orbiting around the Sun.
p.s. I suspect Celestia is not the best program to use to determine the best times for observing cometary flybys. Unless the objective is to learn how to calculate such things, you might want to consider using JPL's Horizons ephemeris server. http://www.ehow.com/how_5522248_calcula ... rbits.html briefly describes a procedure for determining the info you're interested in, although it doesn't provide the specific details.
The orbital parameters which Celestia uses and which you can easily see are those in whatever .SSC catalog is used to define the orbit of the comet that you're interested in. Given those parameters, one could write a Lua (Celx) script to calculate the aphelion and perihelion of a comet. I don't think anyone has written one yet to do that, though.
Note: Apogee and perigee are the distances from the center of the Earth to an object orbiting around the Earth. The suffix helion is used for objects orbiting around the Sun.
p.s. I suspect Celestia is not the best program to use to determine the best times for observing cometary flybys. Unless the objective is to learn how to calculate such things, you might want to consider using JPL's Horizons ephemeris server. http://www.ehow.com/how_5522248_calcula ... rbits.html briefly describes a procedure for determining the info you're interested in, although it doesn't provide the specific details.
Selden