Solar System Calculator - by Don Cross
See also: [ Astronomy Calendar | Sky View ]

Cartesian coordinates
Angular coordinates
Observer's location
 ° lat
 ° long
Real-time update
year mon day hr min sec
Angle display mode
dd° mm' ss"

Show only those objects bright enough to be seen with the naked eye.
Show only objects that are above the horizon.
Include comets.
Include minor asteroids.

Object x y z distance in AU Mag Elong Con

This is a demo page for my Javascript astronomy engine, astronomy.js. The algorithms here are based on formulas mostly from Paul Schlyter's web page How to compute planetary positions. I also used information from the following books:

I obtained orbital elements for the four major asteroids using the JPL Small-Body Database Browser:
1 Ceres, 2 Pallas, 3 Juno, 4 Vesta.

I also added "67P/C-G" in the table for comet 67P/Churyumov-Gerasimenko.

The sky coordinates calculated here will generally be within 2 or 3 arcminutes of accuracy (about one-tenth the apparent angular diameter of the moon), although results will be worse for the asteroids (Ceres, Pallas, Vesta, and Juno) for years before 2010 or after 2020. This is because I calculate asteroid orbits as perfect ellipses that closely approximate their behavior in 2015, but I do not correct for how these orbits drift over time. I intend to update this page every year or two to use the latest orbital elements for these asteroids, so that calculations for nearby dates will always be reasonably accurate. If you need really accurate data for a planet or asteroid, try the JPL HORIZONS System. (These guys were navigating spacecraft through the solar system when I was still playing with GI Joe!)

Other useful astronomy calculation resources: