Google Sky Map Geocentric Coordinates
<p>Since Google Sky Map was <a href="http://code.google.com/p/stardroid/" rel="nofollow">open sourced</a>, I decided I would play around with it and experiment a bit. I have so far worked out that objects like stars, galaxies etc. are positioned using the GeocentricCoordinate class. It's basically just a normalised Vector3. However I have not been able to figure out what kind of coordinate system this is, exactly.</p>

<p>For example, as a test, I tried to draw something with coordinates (0,0,0), but the app just doesn't draw anything. So I tried with (1,0,0) and this appeared at some arbitrary point in space, nowhere near the equator or anything. Different coordinated just give equally arbitrary results.</p>

<p>Hopefully someone has some idea of how this works.</p>
