Skyfield computes positions for the stars, planets, and satellites in orbit around the Earth. Its results should agree with the positions generated by the United States Naval Observatory and their Astronomical Almanac to within 0.0005 arcseconds (which equals half a “mas” or milliarcsecond).

   Written in pure Python and installs without any compilation.
   Supports Python 2.6–2.7 and Python 3.3–3.5.
   Has NumPy as its only binary dependency, the fundamental package for scientific computing with Python, whose vector operations make Skyfield efficient.