python-sgp4

e near the end of the second line that at the current orbit means it does around 15.5 orbits per day. When I implemented my app, I just grabbed some data from a public link with up to date TLE's. Such as this one, for the 100 brightest satellites is a good start for a simple visualization app. https://www.celestrak.com/NORAD/elements/visual.txt Once you have the TLE for a satellite which describes where it was a while ago, you need a function that gives you the current state vector for the satellite, given the time delta since the known state. Far from earth this can be done approximately with simple orbital mechanics, but close to earth you need to account for athmospheric drag and also the uneven or "bumpy" gravitational field. At some point someone devised a set of algorithms for this called the simplified perturbations models in 1988 https://en.wikipedia.org/wiki/Simplified_perturbations_model... Basically current_state = SGP4(old_state, time_since_old_state) Luckily, these functions were released together with a Fortran implementation, so porting it to whatever language you want is fairly straight forward. Here is an example port of SGP4 to python https://github.com/brandon-rhodes/python-sgp4/blob/master/sg...