Barcoding the Stars
Looking up at the night sky, you will see dozens of stars. If you live in a very dark place, you may even see hundreds. The thing that people find difficult to grasp is just how far away these stars are. Our sun is 150 million km away from earth. If you could travel at the speed of light, which is as fastest you can go, it would take 8 minutes to get there. To get to the next nearest star at the speed of light, you would be travelling for 4 years (that's without toilet stops). Other objects are much further away. There are billions of galaxies outside of our Milky Way. Light from one of the nearest takes over 2 million years to reach earth. That is truly a galaxy far, far away. This is the Andromeda Galaxy, the farthest object you can see with the naked eye. We can't get to the stars to study them, so how do we find out how they work? The answer is light. We use telescopes to collect light from the stars and watch them move and change. Some telescopes detect light that we can...