Dwarf planet Makemake has a moon, astronomers find

Makemake, a dwarf planet and one of the largest Kuiper Belt objects discovered to date, has a moon, according to a new study led by astronomers at the Southwest Research Institute (SwRI) and published in Monday’s edition of Astrophysical Journal Letters.

The elusive, dark satellite was difficult to find, lead author Dr. Alex Parker and his colleagues explained in a statement, as much of its orbit is spent almost directly within the glare of the icy dwarf planet due to a nearly edge-on configuration. The newfound moon is believed to be less than 100 miles wide, while Makemake itself is approximately 870 miles across.

First discovered in 2005, Makemake is a football-shaped planet that has a diameter roughly two-thirds that of Pluto’s and his covered in frozen methane, according to the study authors. The new moon, which has been dubbed MK2, is much 1,300 times darker than the Kuiper Belt object that it orbits, and was found using the Hubble Space Telescope’s Wide Field Camera 3 instrument.

“Makemake’s moon proves that there are still wild things waiting to be discovered, even in places people have already looked,” said Dr. Parker. MK2’s detection means that all four of the currently-designated dwarf planets are home to at least one satellite, according to SwRI.

The discovery of Makemake's moon could lead to new discoveries for other objects. (Image Courtesy of NASA/SwRI/Alex Parker)

The discovery of Makemake’s moon could lead to new discoveries for other objects. (Image Courtesy of NASA/SwRI/Alex Parker)

Research could lead to discovery of other previously undetected moons

The authors of the new study are not the first to search for a moon around Makemake, but previous attempts to locate the satellite proved unfruitful. Now, the successful discovery of MK2 has astronomers hopeful that they may also find previously undetected satellites orbiting other large Kuiper Belt objects (KBOs).

Before findings MK2, researchers believed the fact that Makemake lacked a moon meant that it might have escaped a giant impact event during its past. Now, they plan to investigate its density to see if the moon was formed by such a collision, or if the object has been pulled in by the dwarf planet’s gravity. Based on the abundance of moons orbiting KBOs, the study authors believe that impact events are common among these dwarf planets.

The findings will also prove beneficial in other ways, Dr. Parker explained: “With a moon, we can calculate Makemake’s mass and density. We can contrast the orbits and properties of the parent dwarf and its moon, to understand the origin and history of the system. We can compare Makemake and its moon to other systems, and broaden our understanding of the processes that shaped the evolution of our solar system.”

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Image credit: NASA/Hubble WFC3/SwRI/Alex Parker