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Which planets
might support life?

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The first step to find
life in our galaxy

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is locating exoplanets,
planets that orbit other stars.

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But once we find
them, how can we

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tell if they can support life?

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Would we want to go there?

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The Trappist-1 system has seven
Earth-sized planets with three

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of them in the habitable
zone, but we know very little

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about their atmospheres.

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The Hubble Space
Telescope can tell us

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whether these planets have
hydrogen-rich atmospheres

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like icy-gaseous Neptune
or atmospheres more

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like rocky Earth.

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To measure the planet's
composition and atmosphere,

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we need to use a technique
called spectroscopy.

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Astronomers use
spectroscopy to sort light

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into its very
specific components

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since different chemicals
and dust particles give off

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different telltale fingerprints.

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The Webb telescope
has four spectrographs

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which will be trained on
a few lucky exoplanets.

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We'll learn about the
atmospheres of these planets

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by seeing their
fingerprints as a shadow

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against their bright host
star in a similar way

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to the transit technique.

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Life changed the
atmosphere of our Earth

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over time, increasing the oxygen
and decreasing the methane.

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By taking a virtual
sample of the atmosphere

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of these exoplanets, we
can look for evidence

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of carbon dioxide, water vapor,
and methane, signs of life

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as we know it.

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With Webb, we can
scan for evidence

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of biological processes
trillions of miles from Earth.

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So are we alone?

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Webb and future
missions may finally

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help us answer this question.

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