Scientists have detected faintly glowing methane gas hovering above Makemake, an icy dwarf planet that is smaller and more distant than Pluto within the cosmos. Until now, Pluto was the sole known celestial body that far away in the solar system with gas. This revelation, spearheaded by the Southwest Research Institute, was accomplished utilizing the James Webb Space Telescope, a collaborative effort among NASA and its European and Canadian collaborators.

The results imply that Makemake might possess an ultra-thin atmosphere, or methane could be venting from its frozen exterior in plumes, similar to the geysers found on Saturn’s moon Enceladus. This suggests that the small, distant body is not just a frozen remnant, but rather an active and dynamic world. The results are set to be published soon in The Astrophysical Journal Letters.

“Makemake is among the largest and brightest icy bodies beyond Neptune, characterized by a surface predominantly made up of frozen methane,” stated Silvia Protopapa, lead author, in a statement. “The Webb telescope has now unveiled that methane is also found in the gaseous state above the surface, a discovery that renders Makemake even more intriguing.”

Discovered two decades ago, Makemake is named after the Rapanui deity of fertility. It measures only 890 miles across — just two-thirds the dimensions of Pluto. The dwarf planet is located approximately 4.25 billion miles from the sun, taking around 305 Earth-years to orbit. In 2016, astronomers found that it does not traverse alone: NASA’s Hubble Space Telescope monitored a moon orbiting it.

The latest Webb data offer the clearest view to date of Makemake’s surface chemistry. Observations have shown that some regions of the dwarf planet’s frozen exterior are transitioning into gas. Webb identified this as sunlight interacting with the gas molecules causes them to emit a faint luminescence.

The origin of Makemake’s methane is uncertain. Some researchers speculate it may have developed within the dwarf planet through water–rock interactions and subsequently escaped. Others propose it could be residual methane from the formation of the solar system.

Over time, sunlight and radiation decompose methane into more complex molecules. Scientists have already identified some of these on Makemake, including ethane, ethylene, and acetylene, which agree with this process.

However, the findings are not yet able to determine whether the gas originates from an atmosphere or a plume-like cloud. Neither explanation entirely aligns with the data, thus requiring additional Webb observations. If an atmosphere exists, it is exceedingly faint — billions of times less dense than Earth’s and significantly weaker than Pluto’s.

“If this scenario is validated,” stated co-author Emmanuel Lellouch in a statement, “Makemake would join the select few bodies in the outer solar system where exchanges between surface and atmosphere remain active today.”

If the methane does not constitute an atmosphere, Makemake could be discharging “a few hundred kilograms” of methane bursts each second, Protopapa noted, akin to Enceladus, which releases water into space.

Webb and other infrared telescopes have also indicated that regions on the dwarf planet are surprisingly “warm” for such a remote area — around -190 degrees Fahrenheit. Nevertheless, researchers have not observed direct evidence of gas leakage from these warm areas.

If all the clues were connected, one might infer that Makemake has a methane-centered weather cycle, but Ian Wong, one of the co-authors, warns it is too early to draw that inference.

“While the allure to connect Makemake’s various spectral and thermal irregularities is strong,” Wong remarked in a statement, “determining the mechanism behind this volatile activity remains a crucial step in interpreting these observations.”