Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have discovered evidence of gaseous methane on the remote dwarf planet Macemeiki. This finding is detailed in a paper published in the Astrophysics Journal Letter. This discovery challenges the conventional perception of Makemake as a stable, frozen entity. Following Pltune, where gas presence was confirmed, it is now only the second Transneptune object to display this characteristic.
Protopapa et al. Methane gas was detected with Makemake using Webb observations (white). A sharp radiation peak near 3.3 microns reveals methane in the gas phase on the surface of Makemake. The continuum model (CYAN) is overlaid for comparison. An observable spectrum above the continuum indicates a gas emission peak. Image credit: S. Protopapa/I. Wong/SWRI/STSCI/NASA/ESA/CSA/WEBB.
Makemake, also referred to as FY9 and (136472), was identified in 2005 by a team of astronomers at the California Institute of Technology, led by Mike Brown.
This planet of War is situated in a region beyond Neptune, home to a small solar system.
Its radius measures approximately 715 km (444 miles), making it a dimmer and slightly smaller body than Pluto.
It takes around 305 Earth years for this dwarf planet to complete one orbit around the Sun.
Previously observed stellar occultations indicated that Makemake likely lacked a significant global atmosphere, although thin atmospheres could not be completely dismissed.
Meanwhile, infrared observations suggested mysterious thermal anomalies and peculiar characteristics of its methane ice, hinting at the possibility of local hotspots and potential outgassing on its surface.
“Makemake is one of the largest and brightest icy worlds in the outer solar system, with its surface predominantly comprised of frozen methane,” stated Dr. Sylvia Protopapa, an astronomer at the Southwest Institute.
“Webb has revealed that methane is also present in the gas phase above the surface, making Makemake an even more intriguing subject of study.”
“This indicates that Makemake is not an inert remnant of the outer solar system; rather, it is a dynamic body where methane ice is actively evolving.”
The detected methane spectral emission is interpreted as solar absorbing fluorescence, which occurs when sunlight is re-emitted after being absorbed by methane molecules.
The research team posited that this could either indicate a tenuous atmosphere in equilibrium with surface ice, akin to Pluto, or more transient activities such as comet-like sublimation or cryovolcanic processes.
Both scenarios are plausible and align with current data, given the signal-to-noise ratios and limited spectral resolution.
“The inclination to connect Makemake’s various spectra with thermal anomalies is compelling, but identifying mechanisms that enable volatile activities remains essential to interpreting these observations cohesively.”
“Future Webb observations at higher spectral resolutions will aid in determining whether methane originates from thin atmospheres or outgassing processes like plumes.”
“This discovery opens up the possibility that Makemake has a very thin atmosphere supported by methane sublimation,” noted Dr. Emmanuel Lelouch, an astronomer at the Paris Observatory.
“Our best model estimates a surface pressure around 40 K (minus 233 degrees Celsius) and about 10 picobars, which is a hundred billion times less than Earth’s atmospheric pressure, indicating a dilute surface pressure about ten billion times that of Pluto.”
“If this hypothesis is validated, Makemake will join a select group of outer solar system bodies where surface mass exchanges are still actively occurring today.”
“Another scenario proposes that methane is being expelled in plume-like eruptions,” Dr. Protopapa added.
“In this case, our model indicates that methane may be released at a rate of several hundred kilograms per second, comparable to the intense water plumes seen on Enceladus, Saturn’s moon, and significantly larger than the faint steam observed on Ceres.”
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Silvia Protopapa et al. 2025. JWST detection of hydrocarbon ice and methane gas on Makemake. apjl in press; Arxiv: 2509.06772
Source: www.sci.news
