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Music and sound effects

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Planets begin as dense

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knots in a cloud of gas and
dust swirling around a

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star. But how do they go from
something like this ....

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... to something like this.
With the James

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James Webb Space Telescope,
astronomers will be able to
study how planets

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come to be and how they change
as get older.

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After centuries of searching,
astronomers are finding

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exoplanets ... just about
everywhere.

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ranging from giant planets with
masses much greater than

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Jupiter's ... to worlds only a
few times more massive than
Earth.

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But where do the planets we
know

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best fit into the menagerie of
worlds astronomers are finding?

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How did our solar system come
to be the way it is?

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Why is Earth a balmy,
water-rich world -- and are
there

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others like it elsewhere in the
galaxy?

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These are the kinds of
questions astronomers will
address

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with Webb.

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For planets that pass directly
in front of their stars,

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Webb will search for chemical
"fingerprints," identifying

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atmospheric gases like water
vapor, carbon dioxide and

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methane that absorb specific
wavelengths of the star's light.

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Webb will also study the dusty
disks where new

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planets form, revealing how the
chemical compositions of
younger and older

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disks change with time and
identifying

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how these changes are reflected
in the planets we find.

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Such studies will be
revolutionary in their own
right.

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And by applying Webb's
capabilities closer to home,
astronomers

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will better understand
planetary systems.

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For example:

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How do our asteroids, comets,
and other small bodies like
Pluto

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relate to the objects that
create the dusty disks around
other stars?

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The Webb telescope will
determine the chemical and
physical

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properties of these bodies with
unprecedented sensitivity in

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in wavelengths unavailable to
telescopes on the ground.

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By learning more about the
small bodies in our solar
system,

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scientists will be able to
address questions about the
solar system's past

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and compare it to other
planetary systems we find in
similar

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phases of construction. For
example,

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did Earth's oceans arrive by
impacts with small icy bodies?

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If so, is the same process
happening elsewhere

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-- and can we find those
locations?

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Webb also will study the outer
planets and their moons.

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Of particular interest is
Titan, the largest

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moon of Saturn. Now being
explored by NASA's Cassini
spacecraft,

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Titan is as big as the planet
Mercury, possesses

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an atmosphere half again as
thick as Earth's, and frigid
surface

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with lakes of liquid
hydrocarbons. Webb

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will map Titan's chemical
makeup with six times Cassini's

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resolution and monitor the
moon's seasonal changes over a
decade

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or more. Next stop: Uranus.

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When Voyager 2 returned this
image in 1986, the

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planet's south pole was facing
the sun. Few clouds could be
seen.

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But as Uranus neared its
equinox in 2007

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brightclouds suddenly
materialized. So far,

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scientistsare at a loss to
explain this profound
seasonalchange."

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During Voyager's visit, the
northern

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hemispheres of Uranus' big
moons were all in shadow.

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. But when Webb begins service,
the moons' northern halves

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will face the sun and give
astronomers abundant new real
estate

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to explore.

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Three years later, in 1989,
Voyager 2 passed

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Neptune and imaged its strange
dark spot.

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Over the following years,
astronomers have seen the dark
spot disappear ...

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and then reappear. Voyager
easily picked

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out clouds despite Neptune's
greater distance from the sun.

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Why is weather on Uranus and
Neptune so different?

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Neptune's big moon Triton is
unusual, too.

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Nitrogen-spewing volcanoes and
other geological

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forces reshape this frozen
surface in ways we're just

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beginning to understand.

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Comets. Asteroids.

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The outer planets and their
moons -- and beyond them, the
icy

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the icy bodies of the Kuiper
Belt. These objects provide us
with

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the closest and most detailed
look at how our own solar
system evolved.

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The James Webb Space Telescope

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makes it possible to take that
understanding a step farther

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-- to probe the makeup of
nearby planetary systems at
comparable

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distances from their stars. Webb

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will allow astronomers to
directly compare the chemical
and physical

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properties of our outer solar
system with similar zones

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around nearby stars.

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Music