# skyfielders/python-skyfield

Elegant astronomy for Python

Repository: https://github.com/skyfielders/python-skyfield
Canonical: https://ross.abutalabs.com/products/python-skyfield
Language: Python
License: MIT
License Family: permissive
Last push: 2026-08-07T20:19:03+00:00

## Health v2 (maintenance only)
Score: 75/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 96, release rhythm 35, longevity 100
- inputs: {"age_days": 4963, "days_push": 26, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1758, forks 259 (observed 2026-08-28T04:05:32.400590+00:00)

## What it is
Skyfield is a pure-Python astronomy library that computes high-precision, research-grade positions for planets, moons, and Earth satellites using ephemeris files like de421.bsp. It has NumPy as its only binary dependency and offers an elegant API for calculating right ascension, declination, distances, and related celestial quantities.

## Use cases
- compute high-precision positions of planets and Earth satellites
- calculate right ascension and declination of celestial objects
- track satellite passes and positions from a ground location
- generate research-grade ephemeris data for astronomy research
- determine distances between Earth and other planets
- script astronomical calculations in Python

## When to choose
- you need research-grade accuracy for planetary or satellite positions in Python
- you want a simple, elegant API with minimal binary dependencies
- you need compatibility across Python 2 and 3

## When to avoid
- you need general-purpose astrophysics modeling beyond positional astronomy
- you require real-time telescope control or hardware integration
- you need a full-featured astronomy suite with image processing

## Facets
- artifact type: library
- maturity: stable
- function: data-science, math, sdk
- domain: astronomy
- platform: python, cross-platform
- tags: astronomy, ephemeris, satellite-tracking, astrometry, celestial-mechanics, science, python

## Member repositories
- skyfielders/python-skyfield (main) score 75

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:32.400590+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:27:35.222395+00:00, confidence not recorded.
  - readme: https://github.com/skyfielders/python-skyfield (fetched 2026-08-28T04:05:32.400590+00:00, sha 216e7ac63d64)
- Data as of 2026-08-30T08:39:29.467469+00:00.