The first color movies from NASA’s New Horizons spacecraft show Pluto and its largest moon, Charon, and the complex orbital dance of the two bodies, known as a double planet.
Since it was discovered in 1930, Pluto has remained an enigma. It orbits our sun more than 3 billion miles from Earth, and researchers have struggled to discern any details about the dwarf planet. New Horizons is the first mission to Pluto and the Kuiper Belt, a relic of solar system formation beyond Neptune.
Although the two movies were prepared from the same images, they display the Pluto-Charon pair from different perspectives. One movie is “Pluto-centric”, meaning that Charon is shown as it moves in relation to Pluto, which is digitally centered in the movie. (The North Pole of Pluto is at the top.) Pluto makes one turn around its axis every 6 days, 9 hours and 17.6 minutes—the same amount of time that Charon rotates in its orbit. Looking closely at the images in this movie, one can detect a regular shift in Pluto’s brightness—due to the brighter and darker terrains on its differing faces.
The second movie is barycentric, meaning that both Pluto and Charon are shown in motion around the binary’s barycenter – the shared center of gravity between the two bodies as they do a planetary jig. Because Pluto is much more massive than Charon, the barycenter (marked by a small “x” in the movie) is much closer to Pluto than to Charon.
These near-true color movies were assembled from images made in three colors — blue, red and near-infrared – by the Multicolor Visible Imaging Camera on the instrument known as Ralph, a “Honeymooners” reference that classic TV fans can appreciate. The images were taken on nine different occasions from May 29-June 3.
Launched in January 2006 from Cape Canaveral, Florida, New Horizons is less than a month away from its closest fly-by of Pluto and its five moons on July 14, 2015, when the probe will be 7,800 miles from the Pluto system. In early April, the probe sent back to Earth its first color image of Pluto and Charon.
As New Horizons closes in its intended target, the best is yet to come. “Color observations are going to get much, much better, eventually resolving the surfaces of Charon and Pluto at scales of just kilometers,” said Cathy Olkin, New Horizons deputy project scientist from the Southwest Research Institute (SwRI) in Boulder, Colorado.. “This will help us unravel the nature of their surfaces and the way volatiles transport around their surfaces. I can’t wait; it’s just a few weeks away!”