Plate Nº 36 · recorded October 9, 2026
Space & AstronomyReported finding
SPHEREx Telescope Finds Water and Methane on Dozens of Brown Dwarfs
NASA's SPHEREx infrared telescope has found water, methane and other molecules in the atmospheres of 37 brown dwarfs — failed stars that drift through the galaxy alone.
By Nathan Brooks4 min read848 words
In brief
- SPHEREx detected water, methane, carbon dioxide and carbon monoxide in 37 nearby brown dwarfs.
- The observed objects span roughly 4,000 to minus 10 degrees Fahrenheit (2,200 to minus 20 degrees Celsius).
- The space telescope measures brightness in 102 colors from deep red to infrared wavelengths blocked by Earth's atmosphere.
- SPHEREx launched in March 2025 and takes about 3,600 unique images per day of the entire sky.
- The study was published in The Astrophysical Journal (2026), DOI: 10.3847/1538-4357/ae9d66.
NASA's SPHEREx space telescope has detected water, methane, carbon dioxide and carbon monoxide in the atmospheres of 37 nearby brown dwarfs — objects too small to be stars but too massive to be ordinary planets. The findings, published in The Astrophysical Journal, mark the first broad look at these cold, drifting worlds in a band of light that ground-based telescopes simply cannot reach.
Brown dwarfs sit in an awkward corner of astronomy. They form the way stars do, from collapsing clouds of gas, but they never gather enough mass to ignite sustained hydrogen fusion in their cores. Instead, they glow dimly with internal heat and wander the galaxy untethered to any host star.
Astronomers first discovered them in the 1990s. Since then, only a few dozen have been studied in detail with space telescopes, so much of what scientists know about their makeup, storminess and evolution comes from theoretical models rather than direct observation.
What did SPHEREx actually see?
The study team, led by Zafar Rustamkulov of IPAC — Caltech's science and data center in Pasadena, California — analyzed SPHEREx observations of 37 brown dwarfs spanning the full temperature range of the class, from roughly 4,000 degrees Fahrenheit down to minus 10 degrees Fahrenheit (about 2,200 to minus 20 degrees Celsius).
The telescope measures each object's brightness in 102 different colors, from the deepest red visible to the human eye out into the invisible heat of infrared light. That produces a spectrum — essentially a chemical fingerprint of the atmosphere. Across the sample, the spectra revealed atmospheres rich in water, carbon dioxide, carbon monoxide and methane.
"We're seeing the signatures of these molecules and how they change from object to object across the entire temperature regime," said study co-author J. Davy Kirkpatrick, also a scientist at IPAC.
The infrared advantage is decisive here. "From orbit, SPHEREx sees wavelengths of light that are basically impossible to see with telescopes on the ground because water in Earth's atmosphere absorbs them," Rustamkulov said.
Why are these objects so strange?
Rustamkulov describes the targets with unusual affection. "They're kind of goth," he said. "Unlike exoplanets, free-floating brown dwarfs are completely independent celestial objects that will fade into eternity alone. We're still learning how complex they are."
Like Jupiter and Saturn, brown dwarfs are essentially warm balls of gas wrapped in clouds. Unlike planets, they generate their own heat from within rather than absorbing it from a parent star. Some of the objects SPHEREx observed are in a transitional life stage: their exotic clouds thin out and methane-rich atmospheres emerge.
This is where the preliminary results get interesting — and where the current models fall short. The state-of-the-art computer simulations reproduce the broad chemical trends across the temperature range, but they struggle to match the data around these cloudy transitions.
"No two brown dwarfs are alike," Rustamkulov said. "Even at the same temperature, their spectra look quite distinct."
That individuality is a limitation worth flagging: with only 37 objects analyzed so far, researchers cannot yet say how representative this sample is. The team is working through thousands more observations.
Is this the telescope's main job?
Not quite. Spotting brown dwarfs is something of a side project for SPHEREx — short for Spectro-Photometer for the History of the universe, Epoch of Reionization, and ices Explorer. Launched in March 2025 and managed by NASA's Jet Propulsion Laboratory in Southern California, the observatory takes about 3,600 unique images per day and stitches them into maps of the entire sky.
Its primary goals are cosmological and chemical:
- Map the distribution of hundreds of millions of galaxies to reconstruct what happened in the first fraction of a second after the Big Bang.
- Search for the chemical ingredients of life in interstellar ice that could one day seed oceans on distant worlds.
Brown dwarfs enter the picture because the mission's spectral coverage — spanning deep red and infrared wavelengths — happens to be a fruitful window onto their cloudy atmospheres. Previous surveys by NASA's James Webb Space Telescope and the retired Spitzer Space Telescope found many of these objects, but SPHEREx is now imaging thousands of them for the first time in this particular wavelength band.
What comes next?
"Our paper concentrated on just three dozen, but we have thousands more that we are in the process of analyzing," Kirkpatrick said. "I really want to see what bounds the universe places on the variety of brown dwarfs."
He frames the results as "a call to action to explore even more of these dark worlds," while acknowledging the difficulty ahead. "This journey has turned many of us into accidental meteorologists. We know how hard it is to predict weather on our own planet, and we realize it's going to be just as challenging to explain the phenomena we see in these bizarre, cold objects."
The study, Zafar Rustamkulov et al., "SPHEREx 0.75–5 μm Spectra for a Sequence of Nearby Brown Dwarfs," appears in The Astrophysical Journal (2026), DOI: 10.3847/1538-4357/ae9d66.
via Phys.org Space & Astronomy (Source)
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