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Pick any two worlds and see how they measure up, from size and gravity to the length of a day.

First Second

The Solar SystemA field guide for British skies

Everything you need to find your way around our corner of space, written for people looking up from Britain and Ireland. Switch on Night vision at the top of any page before you head outside.

Explore

The planets
Compare worlds
Events calendar
Trivia and quiz
Photo gallery
Contact

From Britain

Tonight from Britain
The Solar System on Britain
Dark sky places
British astronomy

Planet positions are computed in your browser from JPL orbital elements. Figures from NASA fact sheets. Space photographs courtesy of NASA and in the public domain; heritage images from Wikimedia Commons under the licences shown beside them. Map data from Natural Earth.