niamhxox13 to Colm, Eoin, Joseph, Lauren on 20 Nov 2013.
Eoin O Colgain answered on 20 Nov 2013:
A galaxy is just a large collection of stars and between the Milky Way and our nearest spiral galaxy, Andromeda, there are various dwarf galaxies. One can see Andromeda with the naked eye, but binoculars make it easier.
colm bracken answered on 20 Nov 2013:
Hi niamhxox13, great question. Yes about 100 years ago a man called Edwin Hubble realized that some of the fuzzy patches of light in the sky are actually other galaxies. Until that point we only knew of our own galaxy and we thought that this might be the whole Universe.
Hubble also made special measurements of the galaxies called spectra. these spectra allow you to measure the speed that something is moving toward you or away from you at. Hubble realized that most galaxies are flying away from us, and the further away they were the faster they were moving. This meant that the Universe is expanding which was a huge deal.
So yes, we now know that there are approximately 100 billion other galaxies in the observable Universe. Some our like our spiral shaped galaxy, others are kinda ball shaped blobs called ellipsoidal galaxies, while others are irregular shaped giving them the name irregular galaxies!
Lauren Mc Keown answered on 20 Nov 2013:
Hey Niamh, yes there are billions of other galaxies out there, each classified according to how round or flat they appear, whether they are a spiral, are barred in shape and whether they have “spiral arms”. The shape and part of a galaxy you look at can tell you a lot about whether the stars in a particular part are old or young. On top of this, a there are a whole lot of clusters and superclusters which contain hundreds to thousands of other galaxies bound by gravity. Don’t think about that too much because it will start to freak you out – you are part of the only known planet to support life in one solar system, in one galaxy, which is just one of billions of other galaxies!
Joseph Roche answered on 20 Nov 2013:
Yup lots of evidence. In fact, the first person to discover that there are spiral arms in other galaxies was the 3rd Earl of Rosse right here in Ireland. Here is a sketch he made of the spiral structure of the galaxy in the 1840s:
He built a telescope at his castle in Birr, Co. Offaly that was the biggest telescope in the world for more than 70 years. Nowadays we are trying to build a new type of telescope at that same castle in Birr to make Ireland a leader in astronomy again: http://www.lofar.ie/