Orbiting a tiny planet at the far reaches of our solar system is an even tinier, pitch-black moon, NASA's Hubble telescope has revealed.
The moon, which has been dubbed MK2, orbits Makemake, the second brightest icy dwarf planet, after Pluto, in the Kuiper belt, the large mass of frozen rocks, comets and other objects orbiting the sun beyond Neptune.
The discovery of Makemake, along with fellow dwarf planets Haumea, Ceres and Eris, was the primary reason for the reclassification of Pluto in 2006 as a dwarf planet.
Pluto has 5 moons. Haumea has 2 moons. Eris has one moon. It had appeared that Makemake, 890 miles wide and the largest Kuiper belt object after Pluto and Eris, had none.
Michael E. Brown, who is a professor of planetary astronomy at the California Institute of Technology, led the team that discovered Eris, Haumea and Makemake, and the moons of Haumea and Eris, had looked for moons around Makemake, too. He did not find any, but that was not necessarily the end of the story.
A team of astronomers led by Marc W. Buie of the Southwest Research Institute decided to use the Hubble Space Telescope to take a closer look and see what may have been missed. They found a dot next to Makemake ? the moon, which, for now, is designated S/2015 (136472) 1 and nicknamed MK 2.
Alex Parker, research scientist at the Southwest Research Institute in Boulder, Colorado, said when the moon turned up in the data, it was not actually that faint. The moon's orbit is nearly edge-on when seen from Earth. In earlier observations, the moon was, by chance, too close to Makemake and obscured in the glare, he added.
The astronomers estimate that MK 2 was about 13,000 miles from Makemake and orbits about once every 12 days.