Friday, July 24, 2015

All ye heights of Heav'n adore

It says "a mere 2.5 Million light-years away"; this means that light has echoed between us roughly fifty times since Tyranosaurus Rex last stalked ... whatever it was they were after (they were found in layers of rock officially characterized in Crete, rather than those in the Jura), though we've only gone 'round our orbit of our own galaxy a bit more than one turn. For comparision, we record echoes between Earth and Pluto in about nine hours. The Andromeda galaxy spans a wider part of our sky than the moon does (unless you're on the Moon...) and is visible from most of both hemispheres, but it appears much fainter in the spectrum we humans see. It seems to be getting closer to us, too!

Most of the very-round spots in this picture are individual stars of the Milky Way, a thousand times closer to us than Andromeda; the fuzzier blobs include mini satelite galaxies orbiting Andromeda and huger galaxies much further away.


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