The Physics of Raining Sand

A new paper presents an analysis of 113 red and brown dwarf stars that discovered silicate clouds in the cool brown dwarfs

IMAGE: Brown dwarfs — celestial objects that fall between stars and planets — are shown in this illustration with a range of temperatures, from hottest (left) to coldest (right). The two in the middle represent those in the right temperature range for clouds made of silicates to form. CREDIT: NASA/JPL-Caltech

As we find more and more worlds across our galaxy, researchers are focusing more and more on what kinds of environments can support life and what kinds of weather can make existence harder or easier. And it turns out that there are conditions out there that create weather that not even sci-fi writers had led me to expect.

On objects ranging from gas giants to brown dwarfs, there are atmospheric layers that are so warm that stuff that sand is made of — silicates — can form atmospheric layers. And, just like water vapor in the atmosphere can turn into drops that fall as rain, it is possible for the small dust grains to glom together and fall from the sky as pieces of sand.

While it’s believed that Jupiter has this kind of a lawyer deep in its atmosphere, we don’t have the ability to see that layer, so we can’t study that layer directly. To see what is going on, we need warmer objects, and to find those objects, researchers went hunting through the Spitzer Space Telescope archive looking for brown dwarfs. These objects are tens of times larger than Jupiter and may temporarily burn heavy hydrogen — deuterium and tritium — in their cores, but for…