Hubble discovers new moon in our Solar System
A team of astronomershas announced the discoveryof a new moon located in the far reaches of our Solar System,orbiting the little-known dwarfplanet Makemake. Tentatively designated S/2015 (136472), or MK 2 forshort, this newest addition to our little patch of the Milky Waycould shed light on the enigmatic nature of minor planets traversingthe Kuiper Belt.
Makemake isone of five officially recognized minor planets such as Pluto thatare known to roam the Kuiper Belt. Following itsdiscovery in 2005, a number of attempts have been made to ascertainwhether the distant icy body played host to one or more satellitemoons, but each bid had came up empty, until now.
MK 2 had been able toexist undiscovered up until now thanks to the surface characteristicsof Makemake. Much like Pluto, Makemake is coated in a dense layer ofmethane ice. The reflective properties of the ice caused the dwarfplanet to shine up to 1,300 times brighter than MK 2, essentiallycloaking the moon in the glare of the planetoid.
Only with Hubble's high-resolution Wide Field Camera 3 were astronomers finally able topierce through the interference and discover the elusive moon.
MK 2, which isestimated to boast a diameter of only 100 miles (161 km) across,around nine times smaller than Makemake, was spotted orbitingthe dwarf planet at a distance of 13,000 miles (20,921 km). Initialobservations suggest that MK 2 traverses a reasonably circulartrajectory with a 12-day orbital period. Further analysis of themoon's orbit will be needed to confirm this first impression, andsettle the question as to how MK 2 came to settle in orbit aroundMakemake.
Confirmation of acircular orbit would support the theory that, at some point in thelast several billion years, MK 2 collided with Makemake and wassubsequently drawn in to a stable orbit by the dwarf planet'sgravitational pull. Conversely, a more elongated orbit would suggestthat MK 2 was captured following a close proximity pass of theplanetoid that did not involve a direct collision.
The presence of themoon could also provide an explanation for a previous detection ofincreased infrared emissions from the planetoid, which had been takento indicate unexpected warm spots on Makemake's surface. It is nowthought that the instruments, which lacked the resolution to identifyMK 2 as a separate body, were detecting the black surface of the moonin close proximity to Makemake.
It is thought thatunlike the larger planetoid, MK 2's relatively weak gravitationalinfluence was unable to maintain a covering of methane ice,which exposed the moon's charcoal-black surface, and allowed it to becomewarmed by sunlight.
The discovery of asatellite body orbiting Makemake opens numerous possibilities forfurther study of the planetoid. Furthermore, the similarities insofaras the methane ice surface and the presence of a satellite moon ishelping to create a more detailed model for other Kuiper Belt bodies.
Just as observations ofPluto's moon Charon paved the way for for a more accuratedetermination of Pluto's mass, the discovery of MK 2 will allow for amore comprehensive characterization of Makemake, including its density and composition.
Scroll down to view a NASA video on the discovery of MK 2.