It is from the same author. He semi-retired pyephem with the release of this project¹: "The Skyfield astronomy library should be preferred over PyEphem for new projects. Its modern design encourages better Python code, and uses NumPy to accelerate its calculations."
I switched a few toys I'd written from pyephem to skyfield, and it felt like a large improvement. (Must note that they really were toys though, so the amount of work wasn't huge in my case).
In many ways. Pyephem uses the ancient xephem linux C library for its astronomical calculations for both satellites and solar bodies. Skyfield uses the modern NASA SDG4 tables for a more accurate calculation of satellite positions and JPL’s ephemeris tables for planetary positions, yielding much greater accuracy and precision. It is written in pure Python and uses Numpy for speed enhancement. Finally, its API is completely different so knowing pyephem won’t be of much help in learning skyfield.
