Clouds made of sand may scud across the skies of a pair of brown dwarfs – “failed stars” that are among the Sun’s closest neighbors. The clouds move in a hurry – they can change the appearance of the brown dwarfs over just a few hours.

The system is known as Luhman 16. It’s just six and a half light-years away – about two light-years farther than the closest star system, Alpha Centauri. But it wasn’t discovered until about a decade ago because it’s extremely faint. It’s in the constellation Vela, which just peeks into view late tonight for skywatchers in the far-southern United States.

Luhman 16 is a binary, so the two brown dwarfs are locked in orbit around each other. Both of them are about 30 to 35 times the mass of Jupiter, the largest planet in the solar system. That makes them too massive to be planets, but not massive enough to shine as true stars.

The surfaces of both objects are hot, but not nearly as hot as the Sun. That allows molecules to condense and form clouds.

Researchers examined the system with instruments aboard Webb Space Telescope. The instruments are sensitive to different wavelengths of light, so they reveal different details. They found clouds made of silicate – grains of sand. They also found water, carbon monoxide, and methane. The compounds were found at different depths in the atmosphere. So the observations provided a 3-D look at the busy skies of these faint neighbors.

Script by Damond Benningfield