NASA’s New Horizons spacecraft captured this low-resolution view of Styx, Pluto’s smallest moon, on July 13, 2015, from a distance of 391,000 miles (631,000 km).
This composite image of Styx was taken by New Horizons’ Long Range Reconnaissance Imager (LORRI) instrument on July 13, about 12.5 hours before the probe’s closest approach to Pluto, and was received on October 5. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.
Styx was discovered in 2012 by a team of astronomers led by SETI Institute scientist Mark Showalter, during observations of the Pluto system made with the NASA/ESA Hubble Space Telescope.
Also known as P5, Styx lies between Nix and Pluto’s largest moon, Charon.
The moon has a circular orbit and travels once around Pluto every 20 days.
“Although it may not look like much, the new composite image of Styx reveals a highly-elongated satellite, roughly 4.5 miles (7 km) across in its longest dimension and 3 miles (5 km) in its shortest dimension,” said Dr Hal Weaver of the Johns Hopkins University Applied Physics Laboratory, a project scientist for the New Horizons mission.
The measured brightness of the tiny moon, combined with this new size estimate, suggest Styx has a highly reflective, icy surface, similar to what was previously found for Nix and Hydra.
Using the new images, together with other data from New Horizons, the researchers hope to unravel more details about the shape and rotational properties of the moon.
“Ultimately, we hope to learn more about all four of Pluto’s small moons, to understand their similarities and differences, how they formed, and how they evolved,” said Dr Alan Stern of the Southwest Research Institute, principal investigator for New Horizons.
The spacecraft is currently 3.14 billion miles (5.05 billion km) from our planet and 66.9 million miles (107.7 million km) beyond Pluto. It is healthy and all systems are operating normally.
