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How can we find hidden planets?

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The search for planets
around stars other

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than our sun began in the 1990s.

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NASA's James Webb
Space Telescope

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will make that
search even easier.

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Normally, it's a real
challenge to see planets

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around other stars.

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This is the best
picture we have of one

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of these extra-solar planets
taken by the Hubble Space

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Telescope.

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No, not that.

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That's the star.

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The planet is uh, here.

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It's actually easier
to see the dust

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around planets than
the planets themselves

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since there's so
much dust spread out

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over such a vast area.

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This picture captures
visible light from the star

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as it reflects off
the planet and dust.

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But Webb's infrared vision
will detect the inherent glow

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of these objects as they shine
with their own infrared light.

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In fact, Webb will
observe both gas and dust

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in exquisite detail
around these young stars,

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studying and classifying
showers of tiny pebbles

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as they ride lofting
gaseous winds on a collision

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course with each other and
eventually planetary destiny.

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Take a look at this animation.

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In the center is a heavy
ball of gas in the process

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of becoming a sun like star.

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Its gravity drags nearby
gas and dust toward it.

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But because that gas is also
zipping around the star,

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its motion balances
the sun's pole

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and keeps it in a stable orbit.

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This also explains why Earth
doesn't careen into the sun.

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Zooming into the disk we see
small particles in orbit.

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Because the star has drawn
all this material together

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into the same space,
things start to collide.

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Some particles stick
together and develop

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a gravitational pull that
collects more particles.

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Gradually, they form bigger
and bigger objects, planets

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circling their own new sun.

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Astronomers now think that
most of the stars in the galaxy

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have planets around them.

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We can't possibly measure or
detect all of those planets.

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But by understanding
how they form,

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we can begin to predict
the diversity of planets

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out there, including how
many Earths we can expect

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to find orbiting other stars.

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