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Gaia Sky vs Celestia: catalog facts
Gaia SkyCelestia
Free

Free and open source under the MPL-2.0.

Free

Free and open source.

Windows, macOS, Linux Windows, macOS, Linux
  • Uses real scientific catalogs including Gaia star data
  • Handles around a billion objects in real time
  • Free, real-time 3D exploration of space
  • Move freely between planets, stars and galaxies
  • Large datasets need significant download space and capable hardware
  • Aimed at scientific exploration rather than a guided planetarium experience
  • Project website blocks automated visitors with a proof-of-work check
  • A simulator for exploration rather than a structured astronomy course
Downloadable app Downloadable app
Open source Open source
License: MPL-2.0 License: GPL-2.0
No account needed No account needed
Not stated if it works offline Not stated if it works offline

Checked October 1, 2026

Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.