The James Webb Space Telescope (JWST) has provided new insights into the enigmatic "cotton candy" planets orbiting the star Kepler-51, located approximately 2,600 light-years away in the constellation Cygnus. A study, published in The Astronomical Journal on March 16, 2026, reveals that JWST's powerful instruments have confirmed the presence of an extreme atmospheric haze on at least three of the system's super-puff planets, which are known for their exceptionally low densities.
Despite JWST's advanced infrared capabilities, this thick haze prevented the telescope from detecting key chemical signatures, such as water or methane, in the planets' atmospheres. The findings indicate that the haze particles are either highly opaque or much smaller than expected, effectively blocking the light needed for spectral analysis. This presents a significant challenge for characterizing the atmospheric composition of such worlds.
The three planets studied, Kepler-51 b, d, and likely e, are all larger than Jupiter but have masses only a few times that of Earth, giving them densities comparable to cotton candy. The new data helps constrain models of their formation and evolution, suggesting they may be losing their puffy atmospheres over time. The research underscores the limits of even the most advanced observatories when faced with extreme planetary conditions.
