An international team of scientists has used NASA’s James Webb Space Telescope to uncover surprising details about the atmosphere of a strange, giant object in space called SIMP 0136.

This free-floating, Jupiter-sized object is not a typical planet because it does not orbit a star. Instead, it drifts through space on its own, located about 20 light-years from Earth.

Scientists had already observed that its brightness changes over time, but they were unsure why.

Now, thanks to Webb’s powerful infrared instruments, researchers have discovered that these changes are due to a complex mix of atmospheric factors, including cloud layers, temperature shifts, and changes in carbon chemistry—not just clouds alone.

This discovery helps scientists better understand the atmospheres of gas giants, both inside and outside our solar system.

SIMP 0136 is an ideal object for studying planetary atmospheres. Because it does not orbit a star, scientists can observe it without interference from starlight.

It also spins rapidly, completing one full rotation in just 2.4 hours, allowing researchers to gather data efficiently.

Before Webb’s observations, SIMP 0136 had been studied using ground-based telescopes and NASA’s Hubble and Spitzer telescopes. Scientists suspected that its brightness changes were caused by patchy clouds, but they also thought that temperature variations and chemical reactions might play a role. However, they needed more advanced technology to confirm this.

Using Webb’s Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI), the team collected thousands of detailed light measurements over two full rotations of SIMP 0136. These instruments allowed them to see how different layers of its atmosphere changed over time.

The results showed that SIMP 0136 has:

• Patchy clouds at different heights, made of iron and silicate minerals.
• Hot spots at high altitudes, possibly linked to auroras or rising gas from deeper in the atmosphere.
• Shifting carbon chemistry, with gases like carbon monoxide and carbon dioxide changing over time.

By studying SIMP 0136, scientists are learning more about how gas giants behave.

The discovery that different parts of the atmosphere change over time means that when scientists study exoplanets (planets outside our solar system), a single measurement may not tell the full story.

“This is exciting because it shows that molecules like methane and carbon dioxide don’t stay the same everywhere on the planet,” said scientist Johanna Vos. “If we only get one measurement of an exoplanet, it might not represent the entire planet.”

These findings will help astronomers prepare for future studies of exoplanets, especially as NASA’s Nancy Grace Roman Space Telescope launches in 2027 to directly image distant worlds. The research was published in The Astrophysical Journal Letters.