NASA Captures ‘Clearest View Yet’ of ‘Hot Jupiter’ Exoplanet’s Dark Side

by TK Sanders

Astronomers recently developed photos with the “clearest view yet” of an exoplanet near Jupiter called WASP-121b. The exoplanet exists about 850 light years away from Earth. It features incredible, uninhabitable features like titanium rain and clouds made from pure iron.

The exoplanet orbits its star, Jupiter, in just 30 hours — one of the quickest orbits in the galaxy. Scientists believe it to be a massive ball of gas with a perpetual “dark side,” meaning it’s tidally locked. More simply, it does not spin to face all sides of space like some planets. Therefore, obtaining footage of the dark side thoroughly excites planetary scientists, who would love to understand such celestial bodies better.

Some of that research includes determining how water changes physical states when moving between the hemispheres of WASP-121b. Researchers primarily use NASA’s Hubble Space Telescope to explore the galaxy. 

According to ongoing research, while airborne metals and minerals evaporate on the hot dayside, the cooler dark side features metal clouds and rain made of liquid gems, they believe.

WASP-121b was discovered in 2015 and is known as a “hot Jupiter” planet because of its relationship to its parent star.

“Hot Jupiters are famous for having very bright day sides, but the night side is a different beast,” said scientist Tansu Daylan at MIT’s Kavli Institute. “WASP-121b’s night side is about 10 times fainter than its day side.”

Scientists worked with NASA technology to better understand the flow of water around the hot planet

Daylan worked alongside researchers at the Max Planck Institute for Astronomy in Heidelberg, Germany. The international team observed WASP-121b using a spectroscopic camera aboard NASA’s Hubble Space Telescope.

Some of the purposes of the study included measuring temperature changes with varying altitudes and tracking how water circulates between the planet’s day and night sides.

For their observations, the researchers combed through the light data for a specific line, or “spectral feature,” that indicated the presence of water vapor. With the data, the group probed the upper atmosphere of WASP-121b across the entire planet. As a result, they observed the complete water cycle of an exoplanet for the first time.

To compare with our planet, water on earth undergoes a fairly mild transfer of energy in its life cycle. It can become solid, liquid, or gas depending on temperature, and the cycle completes itself when evaporated water condenses into clouds and falls back to Earth, again.

But on WASP-121b, the water cycle is “far more intense,” according to the team. On the day side of the planet, temperatures at nearly 5,000 degrees Fahrenheit rip the water atoms apart. These atoms blow around to the night side, where colder temperatures allow hydrogen and oxygen atoms to recombine into water molecules. The “reconstructed water” then blows back to the day side, where the cycle starts again. The team thinks planetary winds of over 11,000 mph sustain the wild cycle.