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So today we're going to talk about the James Webb Space Telescope, one of the most ambitious things NASA has ever built.

Before we get into the mirror, I want to explain why it looks at infrared at all.

Infrared light passes through the clouds of dust that block visible light, so we can see stars that are still forming.

And the universe is expanding, so light from the very first galaxies gets stretched into infrared on its way here.

It's made of 18 gold-coated segments that unfold once it's in space.