Thursday, March 14, 2013

A matter of perspective ...

This is my favourite astrophoto yet. I took it last week- 16 exposures for a total f 90 minutes. It is Centaurus A, a large, quite close galaxy that has its unusual shape owing to the fact that it is currently in the process of swallowing a smaller spiral galaxy.  At its heart is a supermassive black hole with a mass 100 million times that of the sun.  That sort of size puts things in perspective.

The other issue of perspective, and the reason I really like the photograph, is that you can easily see the foreground stars - the ones in our own galaxy.  The sense of distance is quite acute. 

I say it's a close galaxy, but I'm speaking cosmologically. It's around 13 million light years away, meaning the photons which hit the sensor of my DSLR left Centaurus A and began their long journey to earth at pretty much the same time as this chap, a Sivapithecus, came down out of the trees and on to the African grasslands, and began the complex process of trial and error that led to the tool-use and then ultimately to the invention of the DSLR ... 

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