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"Hubble's Inside the Image: Abell 2744"

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This is an image of a galaxy cluster called Abell 
2744. It’s in the constellation Sculptor. It's  

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also been nicknamed Pandora's Cluster. A bunch 
of galaxies that are all gravitationally bound  

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together. So you can see all of these sort of 
yellow fuzzy galaxies here. They're all very  

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close to each other. And all of these are sort 
of glued together by their mutual gravity. So,  

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the force of gravity is pulling each 
galaxy towards each other galaxy and  

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really sticking them together. You can kind of 
think of these like almost cities of galaxies,  

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since there are so many of them that are living 
in such close proximity. This cluster was observed  

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as part of the Hubble Frontier Fields program. 
That program aimed to image six galaxy clusters  

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with some of the deepest Hubble observations of 
a galaxy cluster that have ever been taken. These  

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are incredibly deep images. These are some of the 
deepest images that we've ever had. Overall, the  

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goal was to really sort of understand the deepest 
physics of how these galaxy clusters are acting  

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as gravitational lenses, uncover what the dark 
matter within these galaxy clusters are doing,  

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and then get a really great look at the galaxies 
behind the cluster. So you can see there are a  

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lot of galaxies in this image that are sort of 
stretched into these little blue arcs. These are  

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all gravitationally lensed galaxies, so they're 
being magnified by the gravity of this massive  

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galaxy cluster. And so that gives us a chance 
to see sort of smaller, fainter objects that  

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would otherwise be completely invisible without 
the aid of this cosmic telescope. And just like  

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a glass lens, it collects a lot more light and 
focuses it back to our telescopes. So we're able  

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to see much fainter galaxies than we otherwise 
would be able to without the aid of gravitational  

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lensing. This really gives us a huge boost 
at being able to see sort of the smallest,  

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faintest objects in the distant universe. 
With this particular galaxy cluster,  

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you're able to see galaxies that are as far back 
as about 12 billion years ago. So we're really  

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pushing back to sort of the early days of the 
universe. Overall, the age of the universe now  

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is about 13.8 billion years. So 12 billion 
years is sort of the early stages of when  

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these galaxies would have been forming.

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Abell 2744

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