Makemake and its dark little moon, known for now as MK2, are shown in this illustration. (NASA/ESA/Alex Parker)
Dwarf planet Makemake, which orbits the sun once every 310 Earth-years, has a dark little moon. About 100 miles across, the moon known as MK2 for now (or S/2015 (136472) 1, more officially) evaded detection for more than a decade, hiding in the glare of its parent planet.
But it couldn’t escape the stare of the sharpest eye in the sky forever: When scientists aimed the Hubble Space Telescope at Makemake for more than two hours in April 2015, they discovered a faint point of light moving through the sky along with the icy world.
Until now, Makemake was the only officially recognized dwarf planet without a moon – a dubious distinction that has now been lost.
Is That…a Moon?
At first, Alex Parker wasn’t sure he’d spotted a new moon in the Hubble observations.
“I was sure someone had seen it already,” says Parker, of the Southwest Research Institute. So, he approached collaborator Marc Buie and asked, “Has anyone seen the moon in the Makemake data?”
Buie’s reply — “There’s a moon in the Makemake data?” — convinced ...