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Gravitational lensing. 

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Look at the Webb telescope's
 first deep field image and you may notice

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some galaxies that are stretched
 or banana shaped.

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They're not actually shaped like this.
 So what makes them look like it?

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Gravitational lensing. 

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Gravitational lensing occurs
 when a celestial object has such a massive

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gravitational pull that it actually warps
 the time and space around it.

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Imagine placing a ball
 on a piece of squishy foam.

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The fabric of space -- 

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the foam -- sinks down
 around the celestial object -- the ball.

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And light that would otherwise travel
 in a straight line 

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follows the bend of the warped space,
 distorting and brightening light

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from behind the celestial object
 -- a galaxy cluster in this case.

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So why do we care? 

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Well, because with a natural 

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magnifying glass,
 we can see even more distant objects.

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00:00:41,266 --> 00:00:43,400
In Webb's first deep field here,
 the banana shaped

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galaxies are actually much farther away
 than the galaxies in the central cluster.

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We see them as stretched
 because their light is being warped

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and magnified by the galaxy clusters
 in front of them.

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And this lets us see much farther than we
 would otherwise be able to.