New Horizons Shares Image of Pluto's Double-Lobed Moon Kerberos
Posted on October 23, 2015
The New Horizons team has shared an image of Pluto's moon Kerberos. The image was created by combining four individual Long Range Reconnaissance Imager (LORRI) pictures taken on July 14, just before New Horizons made its closest approach to Pluto. The image indicates the tiny moon is double-lobed.
The larger lobe of Kerberos is about 5 miles (8 kilometers) across and the small lobe is 3 miles (5 kilometers) across. Overall, the moon 7.4 miles (12 kilometers) across in its long dimension and 2.8 miles (4.5 kilometers) in its shortest dimension. The researchers speculate that the moon may have been formed when two smaller objects merged. Kerberos has a highly reflective surface which suggests it is probably coated with relatively clean water ice.
Kerberos is smaller than astronomers expected. They had tried to estimate the mass of Kerberos by measuring its gravitational influence on its neighboring moons. Kerberos was predicted to be relatively large and massive yet appeared faint because it was thought to be "covered in dark material." The new images surprised scientists by showing a much brighter surface on Kerberos.
New Horizons co-investigator Mark Showalter of the SETI Institute says in a statement, "Our predictions were nearly spot-on for the other small moons, but not for Kerberos."
Pluto has five moons. Charon is by far the largest. Here is a composite that NASA calls the Family Portrait of Pluto's Moons. A larger version of this image can be found here.