Goddard Glossary: Gravitational Lensing

Narration: Katy Mersmann

Transcript:

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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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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.