Makemake, also known as 2005 FY9 and (136472), was discovered in 2005 by a team of astronomers from the California Institute of Technology led by Mike Brown.
This dwarf planet is located in a region beyond Neptune that is populated with small Solar System bodies.

It has a radius of approximately 715 km (444 miles) — just slightly smaller and dimmer than Pluto.

It takes about 305 Earth years for this dwarf planet to make one trip around the Sun.

Previously observed stellar occultations suggested that Makemake lacked a substantial global atmosphere, though a thin one could not be ruled out.

Meanwhile, infrared data of the dwarf planet hinted at puzzling thermal anomalies and unusual characteristics of its methane ice, which raised the possibility of localized hot spots across its surface and potential outgassing.

“Makemake is one of the largest and brightest icy worlds beyond Neptune, and its surface is dominated by frozen methane,” said Dr. Silvia Protopapa, an astronomer at the Southwest Research Institute.

“Webb revealed that methane is also present in the gas phase above the surface, a finding that makes Makemake even more fascinating.”
“It shows that Makemake is not an inactive remnant of the outer Solar System, but a dynamic body where methane ice is still evolving.”

The observed methane spectral emission is interpreted as solar-excited fluorescence, which is the re-emission of sunlight absorbed by methane molecules.
According to the team, this could indicate either a tenuous atmosphere in equilibrium with surface ices — similar to Pluto — or more transient activity, such as cometary-like sublimation or cryovolcanic plumes.