Makemake: The Dwarf Planet Named for an Easter Island Fertility God

Makemake was discovered March 31, 2005, by the team of Michael E. Brown, C.A. Trujillo and D.L. Rabinowitz at the Palomar Observatory in California.

This discovery came as part of a search for trans-Neptunian objects — those that lie beyond the orbit of Neptune. Initially dubbed "Easterbunny" due to its detection shortly after Easter, its provisional name was 2005 FY9 before its status as a dwarf planet was confirmed.

In July 2008, under the expectation that it would prove to be a dwarf planet, it was named Makemake, after the creator god and god of fertility, chief god of the bird-man cult, in the Rapa Nui mythology of Easter Island. The International Astronomical Union (IAU) approved this name in 2008, giving a nod to the Easter Island culture and acknowledging the planet's initial nickname. It is the fourth dwarf planet in our solar system, and the third “plutoid." Plutoids are planets that are found farther from the sun than Neptune. All the known dwarf planets are plutoids, except Ceres, which is located in the asteroid belt.

Situated in the Kuiper belt, a region of space beyond Neptune's orbit teeming with small icy bodies, Makemake follows an elliptical path around the sun, which takes approximately 310 Earth years to complete. Its orbit is slightly inclined compared to the plane of the solar system, a characteristic shared with other Kuiper belt objects.

With a diameter of about 888 miles (1,430 kilometers), Makemake is smaller than Pluto, but remains one of the largest known dwarf planets. Makemake's surface is dominated by frozen methane, giving it a bright, slightly reddish hue. This surface reflectivity, or albedo, is second only to Enceladus, a moon of Saturn. Makemake is composed of rock and ice and is very cold, with an average temperature of around -405 degrees Fahrenheit (-243 degrees Clesius).

The thin atmosphere of Makemake consists of nitrogen and possibly methane. Interestingly, during Makemake's passage in front of a distant star — an event known as occultation — there was no detection of a significant atmosphere, suggesting it might collapse as the dwarf planet moves away from the sun.

Makemake's moon, known as S/2015 (136472) 1 and nicknamed MK 2, was discovered in 2016 by the Hubble Space Telescope. This small moon is roughly 109 miles (175 kilometers) in diameter and orbits Makemake at a distance of nearly 13,048 miles (21,000 kilometers). MK 2 is much darker than Makemake, suggesting a different surface composition or less surface ice.

The discovery of MK 2 offered astronomers an unprecedented opportunity to study this dwarf planet system and estimate Makemake's mass and density. It also hinted at how this tiny moon might have formed: possibly as a result of a collision in the ancient past.

The discoveries of dwarf planet Makemake, along with Eris and Haumea, in the early 21st century sparked a significant debate in the astronomical community about the definition of a planet. These objects are similar in size to Pluto and also reside in the Kuiper belt, blurring the clear-cut distinction between planets and smaller solar system bodies.

In 2006, this led the IAU to redefine the term "planet," introducing a new category — dwarf planet. One of the criterion that separates a planet from a dwarf planet is that a planet has cleared its orbit of other debris, which, in the case of Pluto, has not happened. This redefinition demoted Pluto from its status as the ninth planet of the solar system.

This article was created in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.