Have you ever wondered how we know the distance between Earth
and Proxima Centauri? What about the furthest reaches of the
universe — how do we know they're the furthest? The Royal
Observatory in Greenwich, London currently has an exhibition on
the subject and has uploaded a video that gives a simple
explanation of how astronomers deal with a very complex problem.
Measuring the Universe: from the transit of Venus to the edge of
the cosmos will run until September 2nd 2012, excluding July 7th
- August 5th. Admission is free.