The exoplanet HD 80606 b, which has four times the mass of Jupiter, follows a highly elongated orbit and swings sharply toward its Sun-like host star every 111 days. At the point of closest approach, its atmospheric temperature surges by 1,100 degrees Fahrenheit—a process NASA’s James Webb Space Telescope has captured in real-time for the first time.
Researchers presented their preliminary findings on June 16, 2026, at the 248th meeting of the American Astronomical Society in Pasadena. The study's lead author is Tiffany Kataria of NASA’s Jet Propulsion Laboratory. To observe the planet before, during, and after periastron—the point in the orbit closest to the star—the team utilized the MIRI instrument aboard Webb. In the span of just a few hours, both the temperature and the chemical composition of the atmosphere shift dramatically.
While the Spitzer telescope had previously noted these abrupt changes, Webb has made it possible to distinguish specific molecules like methane and carbon dioxide. This "roasted exoplanet" has become a perfect natural laboratory, as a single pass provides astronomers with data across a variety of temperatures and conditions that would normally require studying many different objects.
Such "hot Jupiters" with highly eccentric orbits are rare, and HD 80606 b remains one of the most extreme cases. Its behavior is prompting a revision of models for atmospheric circulation and cloud formation in gas giants. The data suggests that earlier assessments of the heating involved were underestimated.
The observations were planned years in advance, given Webb’s tight schedule and the planet's eccentric orbit. Scientists now have an extensive collection of spectra at their disposal, and the work is just getting started. Future analyses are expected to produce even more detailed maps of heat distribution and chemical activity on this "toasted" planet.
