On October 8, 2026, NASA announced new results from the SPHEREx space telescope. The instrument, launched in March 2025 and managed by the Jet Propulsion Laboratory, detects thousands of brown dwarfs as it scans the sky.
Brown dwarfs form like stars from collapsing clouds of gas, but they do not have enough mass to sustain hydrogen fusion. These dimly glowing objects resemble giant planets such as Jupiter and Saturn in many respects, yet they drift freely through space without a host star and are heated only from within.
In a paper published in The Astrophysical Journal, scientists analyzed SPHEREx observations of 37 nearby brown dwarfs. The objects' temperatures ranged from about 2200 to minus 20 degrees Celsius. Spectra in 102 colors revealed water, carbon dioxide, carbon monoxide and methane in their atmospheres.
"We see the signatures of these molecules and how they change from object to object across the entire temperature range," noted study co-author Javie Kirkpatrick of IPAC at Caltech. The team is already processing thousands of additional objects.
Lead author Zafar Rustamkulov called brown dwarfs "something like ready-made objects": unlike exoplanets, they are completely independent and gradually fade away in solitude. SPHEREx captures wavelengths that are inaccessible to ground-based telescopes because of absorption by Earth's atmosphere.
The molecular signatures change as the objects cool and age. In the transitional phase, exotic clouds thin out, giving way to methane-rich atmospheres. Current models describe the general chemical trends well, but they do not yet cope with the details of the cloud transitions.
"No two brown dwarfs are alike. Even at the same temperature, their spectra look completely different," Rustamkulov added. Kirkpatrick emphasized that the discovery prompts the study of even more such "dark wanderers."
So what do these cold, independent worlds hide in their chemical diversity?
SPHEREx continues to acquire about 3600 unique images every day, while also mapping the sky and helping in the search for interstellar ice. The mission's data are open to scientists and the public.
