Astronomers have spotted the shiniest known planet in the Milky Way, and it has metal clouds that appear to be raining down titanium droplets.
Exoplanet LTT9779 b, which orbits a star about 262 light-years from Earth, is so reflective it acts almost like a mirror, the European Space Agency (ESA) said in a press release.
This hot metal atmosphere defies astronomers’ rules about how planets this size should act.
“It’s a planet that shouldn’t exist,” said Vivien Parmentier, a researcher at the Observatory of Cote d’Azur.
Hot clouds of molten titanium
Exoplanet LTT9779 b was first spotted in 2020, but it’s only recently that ESA discovered how shiny it truly is.
Thanks to the agency’s CHEOPS satellite, which studies exoplanets, scientists found the planet reflects about 80% of the light it receives.
By comparison, Earth, which is fairly reflective, only bounces back 30% of its sunlight. Venus, the solar system’s shiniest planet, reflects 75% of the sunlight.
Scientists believe the planet’s mirror-like quality is due to the composition of its atmosphere. According to ESA, the metallic clouds surrounding the planet are mainly made up of metals such as titanium and silicate (the stuff used in sand or glass).
“Imagine a burning world, close to its star, with heavy clouds of metals floating aloft, raining down titanium droplets,” said study co-author James Jenkins, an astronomer of Diego Portales University and CATA.
It’s this strange atmosphere which fascinates scientists.
A Neptune-like planet with an atmosphere that shouldn’t exist
Exoplanet LTT9779 b is really close to its star. It is so close it orbits it in just under a day. It’s also very big and very hot, about 3,6oo degrees Fahrenheit, which means it’s similar to Neptune.
And therein lies the conundrum. Neptune is very far away from the sun. Every time a planet has been found orbiting its star that closely before, it has either been a huge gas giant, similar to Jupiter, or a barren tiny rock planet smaller than Earth.
“We expect planets like this to have their atmosphere blown away by their star, leaving behind bare rock,” Parmentier said.
The answer may be in the cloud composition.
“We think these metal clouds are helping the planet survive in such conditions, said Sergio Hoyer from the Marseille Astrophysics Laboratory.
“The clouds reflect light and stop the planet from getting too hot and evaporating. “The planet’s atmosphere and surface are heavier and more difficult to blow off because they contain a lot of metals,” said the scientist.
The findings were published in the journal Astronomy & Astrophysics Monday.
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