Firstly, what is a galaxy? It’s a huge conglomeration of stars held together by gravity. Often, but certainly not always they are in a big spiral, the shape so beloved by science fiction film makers.
How many stars are in a galaxy? This really is a difficult question, our galaxy, the Milky Way has somewhere around 300 million stars, our neighbour the Andromeda galaxy has over 1 trillion stars, it’s a big beggar. There are also plenty of galaxies with less than 1000 stars so size doesn’t come into the description, it’s only whether the star group is held together by gravity.
Is it difficult to see a galaxy? Well that’s another tricky question, it all depends on where and when you go looking. If you live somewhere with truly dark clear skies it’s remarkably easy to see the Andromeda galaxy. Looking north east about halfway up the sky you’ll see a faint blurry blob, this is it, now try looking with binoculars or a telescope with only around 20x magnification and you’ll get a much better view. Please be aware that to the naked eye it will never look anything like it does in a photograph, a photo stores a great many pictures together to build up the wonderful images we see.
How big and how far away is Andromeda? When you’re looking at it in the sky it might seem to take up about the same amount of area as a full moon, buts that’s only under perfect conditions and for young people with exceptional eyesight. For most of us it will be a lot less than that. You are looking at something that’s 2,5 million light years away from us, or to put it another way, you are looking back in time 2.5 million years. When the light set off that we are seeing, homo sapiens didn’t really exist, we were just an early branch of one of many proto humans.
Given that Andromeda is one of the nearest galaxies to Earth and is just one of over a trillion, you might begin to get some idea of just how vast space is.
If you enjoy looking at Andromeda, you might also try and find the Triangulum spiral galaxy it’s not far from Andromeda. Just look down and to the right. This is the third biggest galaxy in our local group after Andromeda and our milky way. Lastly the double cluster galaxies between Perseus and Cassiopeia are well worth finding.
That’s all for this month, dark skies to you all.