Andromeda Galaxy, Our Stellar Neighbour

For those of you who have no idea what galaxies are, Andromeda Galaxy, or M31 (French astronomer Charles Messier in 1771 who had identified a great number of celestial objects, including this one) is a famous galaxy, faily nearby by astonomical standards as it stands 2.4 million light years away. 

For those of you who don't know what a light year is, well, here's the short explanation for it:  Light travels at an amazing speed of 300 000 kilometers per second.  So in other words, you'd have to travel at that speed from our planet for a cool 2.4 million years to get to this neighboring galaxy.  That's a very, very long time... 

What amazes me with M31 is that when you look at the picture, you can say to yourself that the galaxy we lie within, the Milky Way, resembles a great deal like M31.  I always get to wonder about the trillions of objects that are hidden there that will, for now, remain unknown to us.  In this picture, you see the whole galaxy with, at the bottom, a satellite dwarf galaxy that's hovering around it given the massive gravity it exerts.  M31 galaxy contains roughly one trilllion stars, similar in ways to how many there are in our galaxy.  One thing to remember is that our galaxy and M31 are only 2 out of hundreds of billions galaxies.  Impressive isn't it!!  Here's a Wiki link:
http://en.wikipedia.org/wiki/Andromeda_Galaxy