Observations using the Hubble telescope and computer simulations allowed researchers to examine the weather on exoplanet WASP-121b in more detail. Located 880 light-years from Earth, this hot gas planet attracts the attention of astronomers due to its extreme conditions and proximity to its star.

WASP-121b has a mass that exceeds the mass of Jupiter by 16%, and its distance from its parent star is only 3.88 million kilometers (only 2.6% of the distance between the Earth and the Sun). The planet completes its orbit around its star in just 1.27 days, meaning a year lasts only 1.27 Earth days. A unique feature of WASP-121b is that it always faces the same side towards the star. On the constantly illuminated side, the planet’s surface heats up to very high temperatures, reaching 2329 degrees Celsius. This causes the atmosphere to expand and the planet’s radius to increase by 75% compared to Jupiter.

Due to its large size, WASP-121b is an excellent example for observation. Using the Hubble telescope, astronomers examined WASP-121b four times: in June and November 2016, March 2018, and February 2019. In each case, the planet was in different positions, including passing in front of and behind its star. This allowed a team of astronomers led by Jack Skinner of the California Institute of Technology to determine how the brightness of WASP-121b varies at different viewing angles and phases. Now, with this data and the use of computer simulations, astronomers have been able to predict the weather in WASP-121b.

Hubble observations have shown that WASP-121b’s atmosphere is dynamic and changing. The temperature difference between the constantly illuminated and constantly shadowed sides of the planet creates cold and warm fronts, as well as storms and hurricanes. These weather events on the planet change within five days.

“We used the information from these observations to determine the chemical composition, temperature and cloudiness of the atmosphere WASP-121b at different points in time. This gave us an extremely detailed picture of how the planet has changed over time,” said co-author Quentin Shanger.

It’s not the first time astronomers have studied weather on exoplanets. For example, in 2009, they observed another hot Jupiter, HD 80606b, using the Spitzer Space Telescope; this Jupiter orbits its star in a long comet-like orbit for 111 days, causing it to heat up intensely and form massive storms, which then disappears. The planet moves away from the star. But WASP-121b’s meteorology was a significant advance in the study of weather on exoplanets. “The collected data set represents a significant amount of observation time for a single planet and is currently the only consistent set of such repeated observations,” Shange said.

Research the weather WASP-121b It is important for advancing knowledge of planetary meteorology and exoplanet research. The data obtained will help to better understand the processes occurring in the atmospheres of planets outside our solar system and to determine how and how accurately the weather conditions can be predicted on exoplanets.