skyfield

Skyfield: why are these coordinates negative? Question: I’ve an example of how to get a geocentric position of Mars (x,y,z cords) relative to the Earth, using class skyfield.positionlib.Geocentric(position_au, velocity_au_per_d=None, t=None, center=None, target=None) (without accounting for light-travel time or the effect of relativity on the light itself). There it is: t = ts.utc(2022, 9, 16) e …