Paul Rumsey Photography

Saturday 12 March 2011

The Andromeda (M31) Galaxy just how far away is it ?

Recently poormanUK reported finding the Andromeda Galaxy (M31).  A oval misty patch in the NW sky which from poormanUK's mission control near Horsham England is not as reported by many books visible to the naked eye.  This is due to light pollution from Horsham and nearby Crawley and Gatwick airport.
This image is not from my telescope.
Finding Andromeda was elusive even with the 8 inch Dobsonian and confirming it with help from my trusty Android  and Google Sky Map put a smile on my face.  So it's not easy in this location but when you start to look into how far this is away it becomes understandable.  This oval misty patch is around 2.5 million light-years away and also happens to be one of the furthest objects that can  be seen with the naked eyes.  Side note, I have seen Andromeda with my high power binoculars from this location.

As I am fairly new to Astronomy a 'Light Year' does not mean much to me and I start thinking about 'Toy Story' and things like that.  We non-scientists need something else to comprehend these distances. So consider this, if I was flying a jet at 600 mph it would take approximately 3 trillion years to get there.  There is also another way to consider when  poormanUK was looking at Andromeda  he was  effectively looking back in time 2.5 million years. This is simply because it took that amount of time for light to travel from Andromeda and reach my telescope.  So who says were not time travellers.  To me this is a much a better way of thinking how staggeringly far Andromeda is away from us.

Now we have sorted out the distance lets consider what Andromeda is, it is estimated that Andromeda is made up of over one trillion stars or put another way one trillion objects like our own Sun. That in turn means that these Suns could have structure similar to our Solar System and you got it potentially life. Don't think we will prove that tomorrow though.  Another interesting point about Andromeda is that if our eyes could take in the full Andromeda Galaxy it would be six times the size of our full moon.

Interesting point the first photographs of Andromeda were taken in 1887 by Isaac Roberts here in Sussex, England.  Guess light pollution wasn't as bad back then.
Here is his picture. Not bad for over 100 years ago!  Well done Isaac Result!

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