You know why astronomy is cool? Because of things like this:
Galaxy clusters are collections of galaxies held together by their own gravity. We see clusters all over the place, and they’re among the largest structures in the Universe. We can find them at large distances, which means we see them as they (and the Universe) were young — it takes light a long time to travel across the cosmos. Astronomers went looking to find extremely distant clusters of galaxies, and found one at a staggering distance: 12.7 billion light years away!
Here’s an image showing the central part of the cluster:
[Click to bigbangenate.]
Each of those circled red dots is a young galaxy, so distant that the light has been on its way here for more than 90% of the current age of the Universe! And they’re almost lost among all those other stars and galaxies in the image (though their intense red color helps… as to why they’re red, read on).
Finding this cluster was a magnificent achievement. The astronomers used the massive 8.2 meter Subaru telescope to look at large swaths of the sky. They ...
