Thursday, March 10, 2016

The Hubble Telescope Can See the Past


In honor of Throwback Thursday, here's some pretty amazing news: the Hubble Space Telescope has just broken the record for "cosmic distance" and seen the oldest galaxy humans have ever found.  The galaxy, which has been named GN-Z11, is from 13.4 billion years ago, which means it formed only 400 million years after the Big Bang.  In cosmic time, that's not a lot.  I was so excited to learn this because, up until now, it hadn't really occurred to me that we could actually see into the past.  But reading about this recent discovery, it all started to make sense.  Light from faraway galaxies has to travel a very long distance to reach us, "so the further the galaxy, the further back in time we see."  That means that an image of a star one light-year from Earth is an image of it from a year ago.  To get more science-y, here's an excerpt from Mary Bowerman's USA Today article:

"Seeing a picture of a galaxy when it was younger or all the way back to the Big Bang 13-billion-years-away, that light has traveled a long way," he [Patrick McCarthy] said. "It's like digging up a fossil, you see what life was like millions of years ago, it’s almost a fossil of the early universe."
For galaxies that are billions of years away, astronomers can measure the distance to a galaxy by measuring its “redshift,” which is caused by the expansion of the universe, according to NASA.
“Every distant object in the universe appears to be receding from us because its light is stretched to longer, redder wavelengths as it travels through expanding space to reach our telescopes,” according to NASA.When the “redshifted” light from these distant galaxies makes its way close enough for our telescope to capture, the information from the light allows researchers to see the galaxies as they were billions of years ago.
If that isn't cool, I don't know what is.

<3 Frances

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