NASA’s new study deciphers why some exoplanets have clouds made of sand

NASA scientists have found a new interesting subject to study about exoplanets, worlds beyond our solar system. Thanks to the archival data from the now-retired Spitzer Space Telescope, astronomers have zeroed in on clouds of exoplanets. While clouds on some planets are abundant in ammonia and ammonium hydrosulfide, others have clouds composed of silicates, the family of rock-forming minerals that make up over 90% of Earth’s crust.

In the new study, published in the Monthly Notices of the Royal Astronomical Society, scientists have attempted to observe the conditions under which these clouds of small dust gains sand form.

Searching sand-filled clouds

During the first six years of Spitzer’s operations following its launch in 2003, scientists found hints of silicate clouds present in the atmosphere of a handful of planets orbiting brown dwarf stars. Brown dwarfs fall between the category of planets and stars and they aren’t massive enough to kick-start fusion, the process that causes stars to shine.

Notably, the evidence gathered by Spitzer over the same was too weak and the presence of silicate will be confirmed using the James Webb Space Telescope which will be ready for operations this month.

According to NASA’s Jet Propulsion Laboratory (JPL), astronomers gathered more than 100 of those marginal detections and grouped them by the temperature of the brown dwarf. “Understanding the atmospheres of brown dwarfs and planets where silicate clouds can form can also help us understand what we would see in the atmosphere of a planet that’s closer in size and temperature to Earth”, Stanimir Metchev, a professor of exoplanet studies at Western University in London, Ontario, and co-author of the study said in an official release.

Since the clouds for by heating the key ingredient until it becomes vapour, silicate clouds are formed in extremely hot worlds. After grouping the brown dwarfs, the study experts found that all of them ranged from about 1,000°C and 1,700°C, revealing temperatures ideal for the formation of silicate clouds.

“In atmospheres hotter than the top end of the range identified in the study, silicates remain a vapor. Below the bottom end, the clouds will turn into rain or sink lower in the atmosphere, where the temperature is higher”, JPL scientists said in a statement.

Based on the results of the study, scientists now believe that even Jupiter has silicate clouds deep into its atmosphere, a location where the temperature is much higher than the top.


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