Hubble Space Telescope finds dynamic atmosphere on a hot, Jupiter-sized exoplanet

Astronomers have found a dynamic atmosphere on a hot, Jupiter-sized exoplanet (WASP-121 b) by combining several years of Hubble observations.

An artist’s illustration of the exoplanet WASP-121 b based on Hubble data
An artist’s illustration of the exoplanet WASP-121 b along with its host star based on Hubble data. (Image credit: NASA, ESA, Q. Changeat et al., M. Zamani (ESA/Hubble))

An exoplanet is a planet that orbits another star beyond our solar system. Exoplanet WASP-121 b was discovered in 2016 and is located 880 light-years away from the earth.

The exoplanet WASP-121 b takes only 1.3 days to orbit its host star as it is extremely close to its host star (just 2.6% of the Earth-Sun distance!).

Due to its extremely close orbit, the exoplanet WASP-121 b is tidally locked, meaning that the same side of the exoplanet is always facing its host star. It is very similar to our moon, which is tidally locked to our earth, and we always see the same side of the moon in the sky.

As a result, the side of the exoplanet facing star (the ‘day side’) reaches a temperature of 2,150 Kelvin, and a huge temperature difference is seen between the star-facing side and the dark side of the exoplanet, which creates massive cyclones on the exoplanet WASP-121 b.

To make this discovery, the research team assembled and reprocessed Hubble observations of WASP-121 b taken in 2016 (June and November), 2018 (March), and 2019 (February).

The research team has used sophisticated computer modeling techniques to analyze WASP-121 b data of Hubble which can demonstrate any small changes in the exoplanet’s atmosphere.

The team found that WASP-121 b’s atmosphere shows notable differences between observations taken from 2016 to 2019. Most especially, they have found massive weather fronts, storms, and massive cyclones that are repeatedly created and destroyed due to the large temperature difference between the star-facing side and dark side of the exoplanet.

“The remarkable details of our exoplanet atmosphere simulations allows us to accurately model the weather on ultra-hot planets like WASP-121 b,” Jack Skinner, the co-author of this study, said in a statement.

A research paper on this topic has been submitted for publication on January 2, 2024.

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Ashim Chandra Sarkar founded Space & Telescope in 2022. He holds a M.Sc. in physics and has five years of research experience in optical astronomy. His passion for astronomy inspired him to open this website. He is responsible for the editorial vision of

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