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The goals of the Carruthers
Geocorona Observatory

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are to study the nature and
origin of Earth’s exosphere

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and how it evolves over time.

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The exosphere itself is the uppermost layer
of the Earth's atmosphere.

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It's comprised
almost entirely of atomic hydrogen –

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this is the lightest chemical species
in existence.

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And it floats away, essentially, evaporates
off of the top of the atmosphere.

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And when the Sun shines on these atoms,

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they essentially scatter
it off, into all directions.

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And so, it glows like a gigantic halo
around the Earth.

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And so, that's called the geocorona,
that fuzzy halo of light

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that's given off by those
exospheric atoms.

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Many times, we think of the transition between

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the atmosphere and space as being this

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very abrupt boundary where at
one altitude you’ve got atmosphere,

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in the next altitude you have space.

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But in reality, this transition is much more gradual

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and can extend over thousands of kilometers.

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By imaging the geocorona, we can actually answer

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fundamental questions about the size of the exosphere,

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the structure of the exosphere,

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and how it changes over time.

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And all of this in response to the input from the Sun.