Skyfield (astro/py-skyfield) is a Python library for astronomical computations.
It depends on various data files to accurately compute moon phases, planet
positions, etc. Several issues are raised by these data files:

  - If they're not found in the path of the Loader, they're downloaded at
  runtime. Depending on the archive you're requesting, some files might be very
  large, causing a long delay (directly related to your network bandwidth). In
  the case of a web server app, you'd cause a timeout on client's end.

  - They come mainly from 2 sources: NASA's JPL, and the IERS. If one of them is
  temporarily unavailable, you couldn't perform any computation.

  - In some countries, or behind some filtering proxies, some hosts may be
  blocked.

  - These files have an expiration date (in a more or less distant future). As a
    consequence, even if the files are already downloaded in the right path, at
    each runtime you could possibly have to download one or more files before
    making any computation using them.

This package provides at least the most common of these assets.

WWW: https://github.com/brunobord/skyfield-data