Makemake has a moon

By AG Staff Writer / NASA April 28, 2016
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Astronomers using NASA’s Hubble telescope have discovered a 160km-wide moon orbiting distant dwarf planet Makemake.

NASA’S HUBBLE SPACE telescope has spotted a tiny, dark moon orbiting Makemake, the second brightest dwarf planet – after Pluto – in the Kuiper Belt.

The moon, nicknamed MK 2, is estimated to have a diameter of about 160km and was spotted about 20,000km from the dwarf planet, Makemake.

MK 2 was observed this month using Hubble’s Wide Field Camera 3 with the discovery announced yesterday. The incredibly faint, dark moon is the first satellite discovered around the dwarf planet. It is more than 1300 times fainter than Makemake and was almost lost in the dwarf planet’s glare.

The moon discovery adds weight to the idea that most dwarf planets have satellites.

“Makemake is in the class of rare Pluto-like objects, so finding a companion is important,” said Alex Parker of NASA’s Southwest Research Institute in Boulder, Colorado, who led the image analysis for the observations.

Makemake moon

Artist’s concept showing Makemake and its newly discovered moon nicknamed MK 2. (Credits: NASA, ESA, and A. Parker; Southwest Research Institute)

Makemake mysteries

By measuring the new moon’s orbit, astronomers can calculate a mass for the system and gain insight into its evolution. “The discovery of this moon has given us an opportunity to study Makemake in far greater detail than we ever would have been able to without the companion,” Alex said.

The discovery may have also solved one mystery about Makemake – what previously looked like unexpected darker, warmer patches on the dwarf planet’s bright icy surface may have in fact just been the charcoal-black surface of its tiny moon.

Makemake was discovered in 2005 and named after the creation deity of the Rapa Nui people of Easter Island. It is the third-largest known object past the orbit of Neptune and about two-thirds the size of Pluto. Makemake is one of five dwarf planets recognised by the International Astronomical Union and is more than 50 times farther away than Earth is from the Sun.

The Kuiper Belt is a vast reservoir of frozen material left over from the formation of our Solar System 4.5 billion years ago, and is home to several dwarf planets including Pluto.