Another cool astronomy article I wanted to share. This one came from Yahoo News and talks about how scientists have found the oldest galaxy so far. The galaxy is 13.3 billion light-years away. There’s a great video about it here:
So what does this mean? A light-year (光年 kōnen in Japanese, 광년 gwangnyeon in Korean) is the distance light goes in 1 year in a vacuum. In other words, in space, light travels 9,460,730,472,580,800 meters in 1 year. This is 1 light-year. If a star is 10 light-years away, that means the light has been traveling for 10 years to get to Earth. The Sun is 8 light-minutes away, so it takes light 8 minutes to reach Earth.
So, if a galaxy is 13.3 billion light-years away, imagine how many meters that is!!!
But also, this means the light from that galaxy has been traveling through space for 13.3 billion years to reach Earth. In reality, the galaxy may already be dead by now or look very different, but we won’t know for a long time because the galaxy is far away.
But when observing space, distance and time are closely related as you can see. The further away scientists look, the older they can see Universe. It is like rewinding the Universe by going further and further away and see the light from that time. Currently, the Universe is thought to be 13.7 billion years old, so this galaxy existed during the first 400 million years, and scientists have already noticed differences. The galaxy is tiny compared our own Milky Way, and the stars would be somewhat different and has only hydrogen in it. Other elements would be made later.
Indeed, we can also “listen” to the background radiation of the Universe and learn about the earliest moments too:
This background microwave radiation is the furthest and earliest radiation we can detect, and helps provide clues to what happened at the very earliest times of the Universe.