As NASA's New Horizons mission nears its historic rendezvous with the dwarf planet Pluto on Tuesday, we're already being treated to images showing Pluto and its surroundings in unprecedented detail.
On Thursday evening eastern time, NASA released new images showing Pluto and its largest moon, Charon.
The two celestial bodies orbit around a common center of gravity that lies between them. NASA compares them to "a pair of figure skaters clasping hands."
The images show Pluto's surface has a high-contrast blend of bright and dark features, which might be contrary to the popular idea of this distant, frozen world. On Charon, the entire planetary object is covered in a uniform light gray, what a Home Depot paint store marketer might label as "Charon gray."
The color differences may be because Pluto has a significant atmosphere, although it is not comprised of the same quantities of gases as one finds in Earth's atmosphere. Charon has no atmosphere, and its surface is known to be made up of frozen water and ammonia compounds.
“These two objects have been together for billions of years, in the same orbit, but they are totally different,” said New Horizons principal investigator Alan Stern, in a NASA press release.
Charon is about 750 miles in diameter, about half that of Pluto. This makes it our solar system's largest moon relative to its planet.
Its small size has made it impossible for other space-based imagers to capture Charon's surface in much detail, but New Horizons, which launched in 2006 and has traveled nearly 3 billion miles, is now close enough to reveal details on increasingly fine scales.
For example, the brighter areas on Charon might be impact craters, which would be scientifically useful since they could provide clues as to the moon's formation process.
“If we see impact craters on Charon, it will help us see what’s hidden beneath the surface,” said Jeff Moore of NASA’s Ames Research Center, in a statement.