Atmospheric Shifts Detected on WISE 0855
A Jupiter-sized brown dwarf located about 7.5 light-years from Earth features water clouds that actively shift in thickness, providing the first direct confirmation that water clouds on another body are changing thickness over time, researchers at the University of Arizona Steward Observatory revealed.
The object, designated WISE 0855, was initially imaged in 2010 by the Wide-Field Infrared Survey Explorer (WISE) and officially discovered by Kevin Luhman in 2014. While early data made the object appear bluer due to background source contamination, recent observations from the James Webb Space Telescope have mapped its atmospheric properties in unprecedented detail.
Observations Using the James Webb Space Telescope
A team from the University of Arizona’s Steward Observatory utilized the James Webb Space Telescope infrared observatory to monitor the cold brown dwarf continuously for 11 hours. Researchers gathered a spectrum of light every 15 minutes, producing a detailed time-series of the world as it rotates.
Brittany Miles, assistant astronomer at the Steward Observatory and lead author of the study, described the analytical leap provided by the new instrument:
“Before JWST, we only had photometry, which mixed up the effects of clouds, chemistry, and temperature all together.”
By untangling these previously overlapping signals, the research team confirmed that water clouds at high altitudes grow thicker and thinner over time. Simultaneously, deep chemical gases are dredged upward by convection from far below in a process known as disequilibrium chemistry.
Proximity and Planetary Characteristics
At approximately 7.5 light-years away, or about 44 trillion miles, WISE 0855 sits in the immediate cosmic neighborhood. For comparison, the closest star system to Earth, Proxima Centauri, is situated roughly 4.25 light-years away.
Despite possessing water clouds and active weather cycles, WISE 0855 is classified as a brown dwarf rather than a true planet. Weighing in at about twice the mass of Jupiter, the frigid object shares more functional characteristics with gas giants than a terrestrial world like Earth and is not considered habitable.
Mark Marley, director and department head of the Lunar and Planetary Laboratory at the University of Arizona, explained that analyzing the atmosphere functions similarly to looking through a screen door, allowing photons to escape directly into space. The findings from the 11-hour observation window were published in The Astrophysical Journal, expanding current astronomical understanding of how basic physics governs free-floating planetary-mass objects across interstellar space.
