Exoplanet WASP-121b, which resides about 900 light-years from Earth, is an egg-shaped scorcher. Temperatures on the day side of the planet can reach up to 4,600 degrees Fahrenheit. It is so hot that heavy metallic elements, such as iron and magnesium,.
But the night side of the planet has so far remained in the dark (sorry).
In a new study published in the journal Nature Astronomy on February 21, astronomers got their first glimpse of the dark side of the planet using NASA’s Hubble Telescope.
The South African Astronomical Observatory’s telescopes discovered WASP-121b in 2015. The planet, which is slightly larger and heavier than Jupiter, is about to be torn apart by gravitational forces from its star. origin, known as WASP 121. It makes a full orbit of this star once every 1.3 days and is tidally locked – one side is perpetually bathed in starlight, the other always gazes into the space.
“It’s one of the most extreme systems we have,” says Ben Montet, an astrophysicist at the University of New South Wales who was not affiliated with the study. He notes that his extremely hot dayside is hotter than some stars.
Hubble has been instrumental in learning more about WASP-121b’s atmosphere, revealing for the first time in 2017 that it contains water vapor and suggesting that the planet contains a stratosphere – a first. The new study has again turned to Hubble and reveals, in detail, the planet’s atmosphere and how the day-to-night temperature change affects the elements flying around Jupiter’s hot upper layers.
Hubble trained its cosmic eye on WASP-121b for two full orbits of its home star, once in 2018 and a second time a year later. Hubble’s “eye” collects light data, which scientists can break down into wavelengths corresponding to particular elements and molecules. The team searched for water vapor on the dark side of WASP-121b and used it to determine how “cold” the dark side becomes.
The answer: The night side goes down to around 2,200 degrees Fahrenheit. Not very cold in Earth terms, but super cold compared to the day side of WASP-121b. They were also able to calculate wind speeds on the planet exceeding 11,000 miles per hour.
With this information, the team then modeled what other types of chemicals and molecules might exist in the exoplanetary atmosphere. They discovered that the night side likely contained exotic clouds made of iron and titanium, as well as corundum, the same mineral found in ruby and sapphire gemstones on Earth. Clouds are whipped from the night side to the day side and end up in an extremely hostile environment where they condense and fall, like rain.
“All of these exotic compounds are raining down from the planet’s atmosphere,” Montet said. Essentially, if you could survive in WASP-121b, you could see the liquid version of rubies and sapphires falling from the sky.
from NASAis expected to observe WASP-121b later this year. The telescope will assess the planet in infrared and analyze its atmospheric chemistry, giving scientists a better understanding of how hot Jupiters might form and exactly what its atmosphere is made up of.