Time past Periapsis?

mbaucco

Hello,

I am trying to build our solar system in Astrosynthesis and I am having trouble finding this particular term. I have tried googling and I have tried the NASA fact sheets for the planets but I cannot seem to find it. Does this go by another nameor does anyone know where I can find this information?

Thanks!

Ed_NBOS

Periapsis is the point in an orbit where its closest to its parent. I believe Astro views that as the 'start position' for the orbit. So when calculating the position of a body in an orbit, the time past periapsis is the number of days past that point in the orbit at the given epoch (start date). So if its 15, and the epoch is 1/1/2000, it means the plant is already 15 days along its orbit on 1/1/2000.

So to duplicate our system, I would pick an epoch date, and look up the positions of the bodies at that point. You may have to do some conversions. But you should get a good guestimate.

Do keep in mind Astro only does 2 body elliptical orbit calcs. Real planetary orbits are affected by all the bodies in a system (ie, Jupiter affects everything). So if you get it set up in Astro, they won't match with reality after a time.

mbaucco

Thanks!