Illustration of LTT 9779 b, the only known ultra-hot Neptune. This planet orbits so close to its star that its atmosphere is scorching hot, glowing from its own heat while also reflecting starlight. Because it is tidally locked - always showing the same side to its star - one half is permanently in daylight while the other remains in darkness. New JWST observations with NIRISS reveal a dynamic atmosphere: powerful winds sweep around the planet, shaping mineral clouds as they condense into a bright, white arc on the slightly cooler western side of the dayside. As these clouds move eastward, they evaporate under the intense heat, leaving the eastern dayside with clear skies. (Credit: Benoit Gougeon, Universit de Montral) NewsletterSign up for our email newsletter for the latest science newsLTT 9779 b, an exoplanet 262 light years from Earth, always stares directly at the sun. With a surface of nearly 2000 degrees Celsius (about 3632 degrees Fahrenheit), the planet glows bright red while still reflecting starlight. Researchers have called it a rare ultra-hot Neptune.Thanks to images from the James Webb Space Telescope (JWST) published in Nature Astronomy, researchers are now able to see and analyze extreme weather patterns on this intriguing exoplanet, which can help them better understand its unique atmospheric properties.Understanding LTT 9779 b The Hot ExoplanetA 2020 study published in Nature Astronomy first identified LTT 9779 b. The study found that the exoplanet has been tidally locked like Earths moon meaning one side has continuously faced the sun, while the other side has been in constant darkness. Its nearly 30 times the size of Earth and is about 0.01679 astronomical units (AU) from its star. For reference, Earth is 1 AU from the sun, or about 93 million miles, and LTT 9779 b is about 15 million miles away from its sun.The distance from its star is what makes LTT 9779 b so hot, but despite the extreme temperature, the new study used the JWST to identify reflective clouds on the western half of the exoplanet's dayside, which creates a major contrast to the hotter, eastern side.This planet provides a unique laboratory to understand how clouds and the transport of heat interact in the atmospheres of highly irradiated worlds, said Louis-Philippe Coulombe, a graduate student at Universit de Montral's Trottier Institute for Research on Exoplanets (IREx), and lead author of the study, in a press release.JWST and Reflective CloudsThrough the JWST, Coulombe and the research team noticed an asymmetry in LTT 9779 bs dayside reflectivity. The team surmised that this unbalance may be due to strong eastward winds that distribute heat and clouds across the exoplanets surface. This new information redefines how heat can move across a planet and how clouds can form in an atmosphere.For this study, the research team analyzed the exoplanet at different phases of its orbit, monitoring its properties at each phase. They found that reflective silicate clouds formed on the western side of the exoplanet, which is likely why it reflects so much of its stars light.The researchers then combined information from the reflective clouds and the exoplanets heat emissions to form a detailed model of LTT 9779 bs atmosphere. According to a press release, the findings reveal a delicate balance between intense heat from the star and the planets ability to redistribute energy.The research team also noted the presence of water vapor in the atmosphere, which helps give the team a better idea of the exoplanets composition."By modeling LTT 9779 bs atmosphere in detail, were starting to unlock the processes driving its alien weather patterns," said Bjrn Benneke, Coulombes research advisor, an UdeM professor of astronomy, and co-author of the study, in a press release.A Rare Ultra-Hot NeptuneCoulombe and the researcher team have intensified LTT 9779 b as an ultra-hot Neptune, meaning that the exoplanet is roughly the size of Neptune in our Solar System but is positioned much closer to its star. The team explains that the exoplanet resides in the hot Neptune desert and is extremely rare."Finding a planet of this size so close to its host star is like finding a snowball that hasnt melted in a fire, said Coulombe in a press release. Its a testament to the diversity of planetary systems and offers a window into how planets evolve under extreme conditions."These findings can help researchers better understand the unique ways planets form and endure stellar forces.These findings give us a new lens for understanding atmospheric dynamics on smaller gas giants. This is just the beginning of what JWST will reveal about these fascinating worlds, said Coulombe in a press release.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Nature Communications. An ultrahot Neptune in the Neptune desertNature Communications. Highly reflective white clouds on the western dayside of an exo-NeptuneSpace.com. 'Ultrahot Neptune' discovered around sunlike starA graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.1 free article leftWant More? Get unlimited access for as low as $1.99/monthSubscribeAlready a subscriber?Register or Log In1 free articleSubscribeWant more?Keep reading for as low as $1.99!SubscribeAlready a subscriber?Register or Log In