Which planets might support life?
The first step to find life in our galaxy
is locating exoplanets, planets that orbit other stars.
But once we find them, how can we
tell if they can support life?
Would we want to go there?
The Trappist-1 system has seven Earth-sized planets with three
of them in the habitable zone, but we know very little
about their atmospheres.
The Hubble Space Telescope can tell us
whether these planets have hydrogen-rich atmospheres
like icy-gaseous Neptune or atmospheres more
like rocky Earth.
To measure the planet's composition and atmosphere,
we need to use a technique called spectroscopy.
Astronomers use spectroscopy to sort light
into its very specific components
since different chemicals and dust particles give off
different telltale fingerprints.
The Webb telescope has four spectrographs
which will be trained on a few lucky exoplanets.
We'll learn about the atmospheres of these planets
by seeing their fingerprints as a shadow
against their bright host star in a similar way
to the transit technique.
Life changed the atmosphere of our Earth
over time, increasing the oxygen and decreasing the methane.
By taking a virtual sample of the atmosphere
of these exoplanets, we can look for evidence
of carbon dioxide, water vapor, and methane, signs of life
as we know it.
With Webb, we can scan for evidence
of biological processes trillions of miles from Earth.
So are we alone?
Webb and future missions may finally
help us answer this question.