Happy birthday Edwin Hubble... From the archives (and one from this week):

Its exact value has been the subject of debate, but the Hubble Constant is an important figure in modern astronomy. http://www.sixtysymbols.com/

After some early and rather embarrassing problems, the Hubble Space Telescope has transformed our view of deep space. Dr Meghan Gray often works with the HST - and now has her very own miniature version.

Albert Einstein did amazing things with General Relativity - but he famously got it wrong when it came to the expansion of the Universe.