For use with Chapter 17
Reflection and Refraction
Looking Back In Time
Posted May 24, 1999
"A long time ago in a galaxy far, far away..."
No, this isn't the beginning of the latest Star Wars movie. This is what astronomers have recently seen through the Hubble telescope -- a galaxy that is 13 billion
years old. What the astronomers are seeing is not what the galaxy looks like today. They are literally looking back in time, seeing how it appeared 13 billion years ago. This is the
oldest object anyone has seen so far.
But don't start looking up in the night sky just yet. Only a tiny amount of light from the galaxy has actually reached us, and the galaxy is so dim that it is just
a faint speck of ultraviolet radiation. It is not even visible to the naked eye or to most Earth-bound telescopes.
The ability to see extremely distant stars and galaxies has increased dramatically over the last few year. This is mainly due to the Hubble and certain ground-based
telescopes with improved technology. In recent years, astronomers have looked back in time to find other objects, including a 13 billion year old quasar and a 12.3 billion year old galaxy.
While astronomers won't be able to study it in any detail, they can still learn a lot from this new galaxy. According to astronomer Patrick McCarthy, it allows them
to get "a handle on the timing and processes by which the first recognizable galaxies coalesced from the primordial sea of light elements." Still, they may have to wait for better technology
before we are able to study the full detail of the galaxy.
Closer galaxies being observed by the Hubble (19 million to 161 million light -years away) give astronomers a way to see how stars are born. Hubble astronomers are
currently studying star development in 6 different galaxies.
Unlike the spectacular names of familiar galaxies like The Milky Way and The Andromeda Galaxy, this new 13 billion year old galaxy is simply named Sharon. Sebastian
Pascarelle, who helped discover the galaxy, chose the name in honor of his sister who had asked him for years to name something after her.
to find out how far different celestial bodies are from Earth, including the Sun, the other planets, and several stars. Use the speed of light to calculate how old the light is that
we see from these bodies.