A group of scientists, including researchers from the Max Planck Institute for Solar System Research (MPS) in Germany have found new evidence of the presence of a plume of water near Jupiter’s moon Europa. WASP-79b is the subject of a research paper published in The Astronomical Journal, and the scientists studying it have painted a vivid picture of a planet that is just plain wild. If you were to be able to stand on the planet — which you can’t, because it’s a “hot Jupiter” gas giant — you’d notice that the sky isn’t blue like it is on Earth. For a reason that scientists don’t yet understand, the planet’s atmosphere isn’t capable of a phenomenon known as Rayleigh scattering, in which tiny particles capture certain wavelengths of sunlight and turn the skies blue on a clear day. On a planet like WASP-79b with an atmosphere that doesn’t scatter light in such a way, the skies would likely be yellow, according to the scientists. “This is a strong indication of an unknown atmospheric process that we’re just not accounting for in our physical models,” Kristin Showalter Sotzen, first author of the study, said in a statement. “I’ve shown the WASP-79b spectrum to a number of colleagues, and their consensus is ‘that’s weird.’” “Because this is the first time we’ve seen this, we’re really not sure what the cause is,” Sotzen adds. “We need to keep an eye out for other planets like this because it could be indicative of unknown atmospheric processes that we don’t currently understand. Because we only have one planet as an example, we don’t know if it’s an atmospheric phenomenon linked to the evolution of the planet.” So it’s always daytime on the star-facing side, with clear skies. And it’s always nighttime on the night side, where temperatures fall to about 2,700 degrees Fahrenheit (1,500 degrees Celsius) and the sky is continually overcast with iron rain, according to the researchers. Strong wind — gusting at more than 11,000 mph (18,000 kph) — constantly sweeps some of the vaporized iron from the day to night side of the planet. Inside the day-to-night transition zone, clouds appear to form as temperatures begin to drop. “Surprisingly, however, we do not see the iron vapor in the morning” as night transitions back into day, lead scientist David Ehrenreich of the University of Geneva said in a statement. The astronomers concluded the most likely explanation is that it rains iron on the night side. Ehrenreich and his team studied Wasp-76b and its extreme climate using a new instrument on the European Southern Observatory’s Very Large Telescope in Chile. While vaporized iron previously has been detected at an even hotter, more distant Jupiterlike world, it’s believed to remain in a gaseous state around that entire planet, Lovis said. At Wasp-76b, this is the first time iron condensation has been seen, he said. In 2022, ESA’s JUICE mission (Jupiter Icy Moon Explorer) will embark on its journey. MPS will contribute the Submillimeter Wave Instrument (SWI) and the Jupiter Electron and Ion Spectrometer (JEI), one of six sensors from the Particle Environment Package (PEP), to this endeavor. NASA is also preparing the Europa-Clipper mission, which is to be launched in 2023 to the Jovian system. MPS is involved in the mission’s science team.