Hubble discovers dwarf planet Makemake’s moon

27 Apr 2016

A dwarf planet called Makemake far beyond Pluto has just become the latest space celebrity, with an orbiting companion of it spotted for the first time.

Beyond Pluto lies a dwarf planet called Makemake, far smaller than Earth but significant enough to be noticeable amid the tranche of frozen space rocks that make up the perimeter of our solar system.

Named in tribute to the Rapa Nui people of Easter Island, Makemake is one of the five dwarf planets in the Edgeworth-Kuiper belt that the International Astronomical Union actually recognised. And now they recognise its moon.

That’s because the Hubble telescope, a programme that has churned out countless images from peering through space over the past 26 years, has just landed its latest major find.

Called MK 2, Makemake’s moon is 1,300 times fainter than the dwarf it orbits, 13,000 miles in the distance. Makemake, for scale, is 870 miles wide.

Dwarf planets’ key information

Spotting dwarf planets (Makemake was first seen in 2005) provides valuable information to scientists, like scale and mass. Finding their moons multiplies this information impressively.

By measuring the moon’s orbit, astronomers can calculate a mass for the system and gain insight into its evolution. In this case – along with that of Pluto – uncovering the moon also reinforces 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 the Southwest Research Institute, which led the image analysis for the observations.

“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.”

Makemake and its moon, with the Hubble team's annotation

Makemake and its moon, with the Hubble team’s annotation

Westmeath going strong

Both Makemake and Pluto are known to be covered in frozen methane. Now, using MK 2 as a reference, Makemake’s density can be established and many further comparisons with Pluto may emerge.

Never heard of the Edgeworth-Kuiper belt? Well here’s some trivia, it’s named after both a Dutch-American astronomer, as well as one from Westmeath.

As far back as 1938, Kenneth Edgeworth proposed that Pluto wasn’t a planet but most likely a large piece of rubble in a greater belt of cosmic debris left during the solar system’s birth. Gerald Kuiper, 10 years later, agreed.

New Horizons, fresh from its remarkable mission to Pluto, is surging through the belt right now. If you want to see some of Hubble’s other finds check this out.

Main image of a planet via Shutterstock

Gordon Hunt was a journalist with Silicon Republic