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Celestia vs Stellarium: catalog facts
Celestia	Stellarium
Free Free and open source.	Free Free and open source under the GPL 2.0, funded by donations and sponsorship.
Windows, macOS, Linux	Windows, macOS, Linux, Android, iOS
Free, real-time 3D exploration of space Move freely between planets, stars and galaxies	Accurate sky for any location, date and time Simulates the view through binoculars, telescopes and specific eyepieces
Project website blocks automated visitors with a proof-of-work check A simulator for exploration rather than a structured astronomy course	The three-dimensional rendering needs a reasonable graphics card Default catalogues are limited until you download the extra ones
Downloadable app	Downloadable app
Open source	Open source
License: GPL-2.0	License: GPL-2.0
No account needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 21, 2026

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