Exoplanets come in many forms, from dense, rocky planets like Earth and Mars to gas giants like Jupiter and Saturn. But some planets discovered outside our solar system are even less dense than the gas giants and are of a type known informally as super-puff or cotton candy planets. One of the least dense exoplanets known, WASP-107b was recently examined using the James Webb Space Telescope (JWST) and the planet’s weather seems as strange as its swelling.
The atmosphere is higher than the center of the planet, with a thick atmosphere that Webb observed consisting of water vapor and sulfur dioxide. The strangest thing is that Webb also saw clouds of silicate sand, which suggests that sand will rain between the upper and lower layers of the atmosphere. This planet is almost as big as Jupiter but its mass is as small as Neptune.
“JWST is revolutionizing exoplanet characterization, providing unprecedented insights at remarkable speed,” the study’s lead author, Leanne Dessin of KU Leuven, says in a statement. “The discovery of sand, water and sulfur dioxide clouds on this fluffy exoplanet by JWST’s MIRI instrument is an important milestone. “It reshapes our understanding of planetary formation and evolution, shedding new light on our solar system.”
It is important to understand the planet’s formation and evolution because it seems unlikely that it would have formed in its current location. It is believed that it formed further into the constellation and migrated inward over time. This may allow its extremely low density. Its orbit close to its star means its temperature is extremely high, with its outer atmosphere reaching 500 degrees Celsius. But those temperatures are generally not hot enough to form silicate clouds, which would be expected to form in lower layers where temperatures are higher.
Researchers believe sand rain is evaporating in lower, warmer layers and silicate vapor rises up into the atmosphere and condenses again to form clouds and fall as rain, similar to the water cycle on Earth. .
“The value of JWST cannot be overstated: wherever we look with this telescope, we always see something new and unexpected,” said fellow researcher Paul Mollier at the Max Planck Institute of Astronomy. “This latest result is no exception.”
This research will be published in Nature Journal.