Astronomers Find First Planet With Earth-Like Water And Weather Outside Our Solar System

Through recent observations, astronomers have discovered that an exoplanet — technically a brown dwarf — which we've known about for years, is much more like our home planet Earth than previously believed. The world, designated WISE 0855, has water clouds that are changing thickness, indicating that it also has progressive weather. WISE 0855 is a Jupiter-sized brown dwarf located about 7.5 light years away. Imaged all the way back in 2010 by the Wide-Field Infrared Survey Explorer (WISE), it was officially discovered by Kevin Luhman in 2014 while looking through the data. Initial observations revealed WISE 0855 to appear bluer than it actually is because the imaging was contaminated by background sources. The recent observations revealed much more, including the water and cloud cover patterns.

The University of Arizona's Steward Observatory team, responsible for the newest discoveries, used the James Webb Space Telescope infrared observatory to watch the brown dwarf for 11 hours. During that time, they gathered a spectrum of light every 15 minutes essentially capturing a timed-series of the world. They shared their findings in a study published in The Astronomical Journal.

With the JWST, the Steward Observatory team noticed clouds coming in and out of focus, changing over time as WISE 0855 rotates — though things work a little differently than the simple weather changes back home since the atmosphere contains gases rising from deep below. Ultimately, WISE 0855 likely isn't a habitable world and is probably much closer in similarity to Jupiter than to Earth. In addition, brown dwarfs like WISE 0855 aren't considered to be true planets.

We've found clouds on other planets — Mars has them during its nighttime, and there's another planet out there with hellish metal clouds swarming its atmosphere. So, the cloud details of WISE 0855 aren't necessarily the highlight of this news. There are two other, very exciting facets to this discovery.

The first is that WISE 0855 is only 7.5 light years away — about 44 trillion miles — and alongside the fact that it's the coldest brown dwarf ever discovered, it's also relatively close, cosmically speaking. To give a comparison, astronomically, the closest star system to Earth is Proxima Centauri, which is about 4.25 light years away. WISE 0855's distance puts it in just about the same neighborhood — a mere 3.25 light years further than Proxima.

The other notable element is that the James Webb Space Telescope was able to detect the clouds, their movement, and their general composition to allow for true observations. This is the first time a team like this has been able to confirm water clouds and also observe them actually growing thicker and thinning out. One of the researchers from the Steward Observatory team, Brittany Miles, said it best. Before James Webb, astronomers and researchers only had access to photometry technologies, which "mixed up the effects of clouds, chemistry, and temperature all together." Now, all of those properties can be distinguished and observed. It's also what helped the team better understand WISE 0855 and its actual makeup versus previous investigations.