Pluto And Charon Float In Space Together In Latest Tantalizing Images

by Sophia Nasr, @Pharaoness

New Horizons was about 3.7 million miles (6 million kilometers) from Pluto and Charon when it snapped this portrait late on July 8, 2015. Most of the bright features around the edge of Pluto are a result of image processing, but the bright sliver below the dark "whale," which is also visible in unprocessed images, is real. Credits: NASA-JHUAPL-SWRI

This is the same image of Pluto and Charon from July 8, 2015; color information obtained earlier in the mission from the Ralph instrument has been added. Credits: NASA-JHUAPL-SWRI

In the latest tantalizing images from NASA's New Horizons spacecraft, Pluto is joined by its large moon Charon. The two have 'floated' in space together for billions of years, orbiting around a common center of mass that lies above the surface of Pluto. The two bodies are thought to have been formed when a proto-Pluto and a proto-Charon collided. The latest images, taken on July 8th by the Long Range Reconnaissance Imager (LORRI), show how astoundingly different Pluto and Charon are from each other.

Pluto's surface has high-contrast color changes throughout its surface, including the darker whale-shaped area across its equatorial region that might be composed of dark organics like the Saturnian moon Iapetus's dark "splat". Charon on the other hand has a relatively uniform surface everywhere except for a darkened pole. Unlike Pluto, which is covered with ices made of nitrogen, methane, and carbon monoxide (all components of its atmosphere), Charon's surface is dominated by less volatile water and ammonia ices, and appears to have no atmosphere. Also notable are the differences in general color. Pluto has a reddish brown color, and Charon is gray.

"These two objects have been together for billions of years, in the same orbit, but they are totally different," said Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), Boulder, Colorado.

Image of Pluto only from New Horizons Long Range Reconnaissance Imager (LORRI), July 8, 2015. Most of the bright features around the edge of Pluto are a result of image processing, but the bright sliver below the dark "whale," which is also visible in unprocessed images, is real. Credits: NASA-JHUAPL-SWRI

Image of Charon only from New Horizons Long Range Reconnaissance Imager (LORRI), July 8, 2015. Credits: NASA-JHUAPL-SWRI

Charon's diameter is about 1200 km (750 miles), just over half that of Pluto, and 12% its mass. Pluto and Charon have by far the largest moon-to-planet size ratio in the solar system and the two bodies are often called a "double-planet". The latest images are beginning to reveal a crisper view of Charon, whose smaller size and lower contrast surface features have made it more difficult for New Horizons to image compared to Pluto.

Members of the mission's Geology, Geophysics and Imaging team (GGI) think the bright areas revealed in the latest images of Charon may be impact craters. "If we see impact craters on Charon, it will help us see what's hidden beneath the surface," said GGI leader Jeff Moore of NASA's Ames Research Center. "Large craters can excavate material from several miles down and reveal the composition of the interior."

"Charon is now emerging as its own world. Its personality is beginning to really reveal itself," said John Spencer of SwRI.

Only 5 days away from its closest approach, New Horizons is currently 5.3 million km (3.3 million miles) from Pluto. New Horizons will come as close as 12,500 km (7,770 miles) from Pluto's surface at 7:50 a.m. EDT on July 14, imaging the dwarf planet in unprecedented detail.

For the original press release, click here.

Sophia Nasr is an astrophysics student at York University. Actively involved in the astronomical community at York U, she is the President of the Astronomy Club at York University and a member of the team at the York University Observatory. She also is involved in university projects, and holds a position in research on dark matter at York U. Holding scientific outreach dear, Sophia is actively involved in social media outlets such as Facebook, Twitter, and Google Plus, where she shares with the world her passion for the universe and how it works.