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<\/p>\nIn a new study from a group of researchers in Canada, data from NASA\u2019s now-retired Spitzer Space Telescope was used to determine the conditions under which silicate clouds form on distant exoplanets outside of our solar system \u2014 giving scientists insight into what\u2019s inside the atmospheres of exoplanets similar in size, temperature, and composition to Earth.<\/p>\n
The study, led by Genaro Su\u00e1rez of Western University in London, Ontario, was released just weeks before the now-operational James Webb Space Telescope\u2019s first images were released on July 12. One of Webb\u2019s first images is spectral data of exoplanet WASP-96b, which, to the surprise of Webb teams, revealed clouds and haze inside the exoplanet\u2019s atmosphere and gave scientists a small glimpse into what Webb can do when observing exoplanets.<\/p>\n<\/p>\n
Spitzer reveals how silicate clouds form<\/p>\n
On Earth, we\u2019re used to seeing clouds made of water molecules. However, on other planets and moons inside and outside our solar system, clouds come in many different chemical makeups.<\/p>\n
On large gas giants, like Jupiter or Saturn, many clouds are made of ammonia and ammonium hydrosulfide, giving them (and their planets) a yellowish hue. On planets similar to Mars, clouds can be made of both water vapor and carbon dioxide depending on atmospheric conditions. However, some exoplanets, or planets located outside of our solar system, have clouds composed of silicates, which are rock-forming minerals that comprise a large portion of Earth\u2019s crust.<\/p>\n
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This image, taken by NASA\u2019S Curiosity Mars rover, shows Martian clouds above a surface outcrop named \u201cMont Mercou.\u201d (Credit: NASA\/JPL-Caltech\/ MSSS)<\/p>\n
Up until the release of the Su\u00e1rez et al. study, scientists had little information on the conditions in which these silicate clouds form. However, using data from Spitzer, the researchers may now have an idea.<\/p>\n
For the study, Su\u00e1rez et al. used observational data of brown dwarfs collected by Spitzer. Brown dwarfs are celestial bodies that are stuck in a state between a planet and a star, and though they form like stars, are not large enough to kick-start fusion within them. This gives brown dwarfs atmospheres that are extremely similar to gas giants, so these odd celestial bodies can be used as a sort-of proxy for exoplanets with clouds.<\/p>\n
Spaceflight history books (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n \u201cUnderstanding 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\u2019s closer in size and temperature to Earth,\u201d said co-author Stanimir Metchev, a professor of exoplanet studies at Western University in London, Ontario.<\/p>\n But first, how do rock-based silicate clouds form on exoplanets?<\/p>\n The cloud-forming process on exoplanets is actually very similar to how clouds form on Earth and other terrestrial planets like Mars. The process starts with a key element or compound, such as water or ammonium, being heated until it becomes a vapor. Then, after being trapped and cooled to a certain temperature, that element or compound will turn into a cloud.<\/p>\n On planets with silicate clouds, the planet\u2019s surface or atmosphere would need to be extremely hot, as rock typically needs to be at a much higher temperature than other elements and compounds to vaporize into a gas. This means that these silicate clouds are only able to form on exoplanets that are extremely hot. Thankfully, brown dwarfs are failed stars and are extremely hot, which made them a great candidate for the Su\u00e1rez et al. study.<\/p>\n<\/p>\nSee Also<\/h4>\n
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