WISE 0855 Weather Patterns Revealed by James Webb Space Telescope
Using the James Webb Space Telescope, astronomers have captured the first direct confirmation that water clouds on a nearby world are changing thickness over time, mimicking weather patterns on Earth. Brittany Miles, an assistant astronomer at the University of Arizona Steward Observatory, led a team that spent 11 hours observing WISE 0855, the coldest known brown dwarf, collecting a spectrum of its light every 15 minutes.
The study, published in The Astrophysical Journal, reveals that the atmosphere of WISE 0855 is driven by two simultaneous processes: water clouds at high altitudes shifting in thickness as the object rotates, and deep chemical gases being dredged upward by convection. Located just 7.5 light-years away, the Jupiter-sized object sits at a frigid 265 Kelvin, making it colder than Earth’s surface and blurring the line between planets and stars.
Webb telescope tracks temperature differences on WISE 0855
Decoding the atmosphere of WISE 0855 required looking through what co-author Mark Marley, director and department head of the Lunar and Planetary Laboratory at the University of Arizona, described as a screen door. As the brown dwarf rotates, different patches of its surface rotate into view with varying cloud cover and temperatures. The medium-resolution spectrograph on the James Webb Space Telescope tracked these temperature differences across individual molecular features, capturing a rhythmic, wave-like signal tied to carbon monoxide and phosphine.
These chemicals fluctuate because internal heat churns them upward from deep layers, a process known as disequilibrium chemistry. While similar convective mixing is well-documented on Jupiter, the telescope allowed researchers to watch the chemical variations happen in real time, molecule by molecule. By untangling the overlapping signals of clouds, chemistry, and temperature, the team established that the basic physics governing Jupiter also applies to cold, free-floating worlds beyond our solar system.
Frequently Asked Questions About WISE 0855
What is a brown dwarf and how does it differ from a planet?
Brown dwarfs occupy a middle ground between planets and stars, possessing too much mass to be planets yet lacking enough mass to ignite as stars. WISE 0855 sits at the very bottom of this category at roughly twice the mass of Jupiter, glowing dimly with leftover heat from its formation.
Why was it impossible to study these weather patterns before the James Webb Space Telescope?
Older telescopes relied solely on photometry, which measured total light output but mixed together the individual effects of clouds, chemistry, and temperature. The medium-resolution spectrograph on the James Webb Space Telescope enabled researchers to isolate these variables for an object as cold as 265 Kelvin for the first time.
How far away is WISE 0855 from Earth?
WISE 0855 is located approximately 7.5 light-years away from Earth, making it an ideal laboratory for studying gas giant atmospheres.
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