NASA's New Horizons spacecraft has provided new images of Pluto's tiny moon Kerberos, finally completing the dwarf planet's "family portrait" of moons.
The observations show Kerberos is even smaller than researchers previously estimated and has a highly reflective surface, Johns Hopkins University reported. The findings contradict predictions made during the spacecraft's July flyby.
"Once again, the Pluto system has surprised us," said New Horizons Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory.
In the stunning new images, Kerberos appears to have a "double-lobed" shape: with the larger lobe measuring in at about five miles across and the smaller one at only three miles. The researchers suggested that the unusual shape suggests a merger of two smaller objects formed the tiny moon. The reflective surface is similar to what has been seen on Pluto's other moons, and suggests the object is likely coated in clean water ice.
Before New Horizon's recent encounter with Kerberos, scientists attempted to "weigh" the moon by looking at its gravitational influence on Pluto's other moons. They found that despite Kerberos' faint appearance, it imposed a surprisingly strong gravitational pull on these neighboring objects. These findings led the researchers to the theory that Kerberos was relatively large and massive, but a surface characterized by dark material caused it to seem faint and small. These new images reveal a small and bright-surfaced Kerberos, and reason behind this original misconception remains a mystery.
"Our predictions were nearly spot-on for the other small moons, but not for Kerberos," said New Horizons co-investigator Mark Showalter, of the SETI Institute in Mountain View, California.
