From Citizendium, the Citizens' Compendium
- Outer space : The relatively empty regions of the universe outside the atmospheres of celestial bodies.
- Astronomy : The study of objects and processes in the observable universe, e.g. stars, planets, comets or asteroids.
- 67P/Churyumov–Gerasimenko : Add brief definition or description
- Halley's Comet : Add brief definition or description}}
- Rosetta (comet orbiter) : Add brief definition or description
- Philae (comet lander) : European Space Agency device which landed on the nucleus of a comet on 12th November 2014; sent with the Rosetta orbiter on 2nd March 2004.