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{Music throughout] This is KELT-9 b.

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It’s about twice the size of Jupiter and it’s always superhot, taking

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only 36 hours to orbit its star. It receives 

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44,000 times more energy than the Sun delivers to Earth,

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making it one of the hottest planets known, with a dayside temperature hotter

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than the surfaces of some stars. This causes its atmosphere to

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boil away into space. Now, thanks to observations

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from NASA’s TESS satellite, we know KELT-9 b is even weirder.

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TESS spots dips in starlight whenever a planet passes in front

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of its star from our perspective. Astronomers call these dips transits.

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But KELT-9 b’s odd star complicates things.

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It spins so fast it’s squished into an oval. This makes

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its poles hotter than its middle, a property scientists call

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“gravity darkening.” The planet’s orbit, also odd, carries it over

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the star’s poles. Combined, these effects make the start of each

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transit different from its end, making further study difficult.

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A team led by NASA Goddard scientists used TESS observations

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to disentangle these effects and provide further insight into the system.

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The polar orbit and gravity darkening give KELT-9 b

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an unusual type of season. Summer occurs when it passes

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over the star's hot poles. Winter — such as it is — 

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happens when it passes the cooler equator. And for every 36-hour orbit,

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which is KELT-9 b’s year, the planet experiences

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these seasons twice ... and each is less than 9 hours long.

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Scientists expect the frequently changing temperatures produce wild

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winds, and they’re busy modeling KELT-9 b’s atmosphere.

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Thanks to TESS, astronomers are equipped to learn more about this

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curious system, and others like it.

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Explore: solar system & beyond

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