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How do we find exoplanets?

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Since planets are close
to much brighter stars,

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how do we actually find them?

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Some planets are found
by a technique that

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uses Einstein's theory
of general relativity,

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observing the bending effect
of gravity from a hidden planet

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as it warps the light
around its host star.

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The most common method is to
look for an eclipse or transit

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as a planet passes in
front of its host star.

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This is how the Kepler
observatory found planets

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by staring at a large
region of the sky

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and waiting for planets to
pass in front of their stars,

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taking snapshots every second.

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The Transiting Exoplanet
Survey Satellite

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uses the same technique on
our nearest neighbor stars.

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Another technique observes
very small changes

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in the star's
position in the sky,

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the wobble that occurs when an
unseen planet's gravity tugs

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on its host star.

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If the planet and
star are oriented so

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that the star is moving toward
or away from us instead of side

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to side, we can
detect the planet

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as a shift in the star's light.

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As far as getting pictures
of the actual exoplanets

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themselves, it's possible,
but very difficult.

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The telescope has to block
the bright stars' light

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to reveal the faint
planet nearby.

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