When we cast our gaze across the galaxy looking for planets that may host even the faintest signs of life, there are obvious non-candidates.
But no planet screams "There's nobody home" quite like KELT-9b. The planet, which resides some 670 light-years away, was first spotted in 2017 — and quickly written off as a candidate for life.
As NASA puts it, "KELT-9b will stay firmly categorized among the uninhabitable worlds."
That's because KELT-9b is the hottest planet ever detected, boasting a temperature of about 7,800 degrees Fahrenheit, or 4,300 degrees Celsius. That kind of heat would make a few stars blush.
In fact, a study published in Astrophysical Journal Letters this month suggests not even a molecule can withstand the planet's fiery furnace.
The research notes that on the side of KELT-9b that always faces its sun, hydrogen molecules are physically torn to shreds. Those fragments then seep to the other side of the planet — called the "nightside" — where they reform. When that hydrogen returns to "dayside," its molecules are once again torn apart.
Sounds like the classical depiction of hell, only for bad molecules, but scientists have a more technical name for it: Ultrahot Jupiter.
That's the designation for planets that are in the same size range as our own gas giant, and also in an extremely tight orbit with their star. KELT-9b more than fits the bill, with about three times the mass of Jupiter and an orbit that sees it skirt its sun in just a day and a half.
(You can watch a fascinating NASA animation of a hot Jupiter in action here.)
"This kind of planet is so extreme in temperature, it is a bit separate from a lot of other exoplanets," the study's lead author Megan Mansfield of the University of Chicago notes in the NASA press release. "There are some other hot Jupiters and ultra-hot Jupiters that are not quite as hot but still warm enough that this effect should be taking place."
And although a place that can't even hold a molecule together for long won't be a prime candidate for alien life, that doesn't mean KELT-9b can't teach us a thing or two. Its star-like qualities, for example, could help scientists test theories about heat recirculation. There's also the planet's penchant for vaporizing heavy metals. Earlier research published in Nature determined KELT-9b was the first known planet with molten iron in its atmosphere — an iron sky, if you will.
KELT-9b just may be the perfect planetary lab for helping us understand processes previously known only to occur in stars.
And don't feel too bad for those molecules in a constant state of being smashed and reformed.
All stars and planets must someday die. Their torment won't be endless.