NASA's New Horizons spots Pluto's faintest known moons

Finally, a family portrait of Pluto is beginning to emerge! For the first time ever, astronomers have captured two never-before-photographed moons orbiting Pluto.

NASA's New Horizons spacecraft photographed Kerberos and Styx -- the smallest and faintest of Pluto's five known moons -- which had only been discovered in the last four years. Following the spacecraft's big revelation of just how enormous Pluto's moon Charon was in 2013, New Horizons is now within sight of all the known members of the Pluto system, according to NASA.

Now, these objects are also so very small. Styx is thought to be the smallest moon of the dwarf planet, measuring only 4 to 13 miles in diameter, and Kerberos slightly bigger at about 6 to 20 miles in diameter. Pluto itself is estimated to be only about 66 percent the size of our moon, at a tiny 1,432 miles in diameter.

"New Horizons is now on the threshold of discovery," said mission science team member John Spencer, of the Southwest Research Institute in Boulder, Colo. "If the spacecraft observes any additional moons as we get closer to Pluto, they will be worlds that no one has seen before."