Today’s gift from the New Horizons flyby is our first-ever look at the surface of Pluto’s enormous moon Charon. The icy world is distinctly different from its parent, and is guarding its secrets closely.
The New Horizons probe has been slowly creeping up on Pluto for nearly a decade. After a heart-stopping computer error threw it into safe mode over the holiday weekend, it’s now back up to full functionality and greedily gobbling data as it nears its closest-approach to the dwarf planet. Now we’re officially in the Pluto flyby stage of the New Horizons mission, which means that literally every day we’re getting the newest, best photos of the Pluto-Charon system. Yesterday, we discovered the tiny red world has a cheeky heart luring our affections. Today, we’re getting our first peek into the mysteries of Pluto’s moon, Charon.
The image was taken late on July 8, 2015 when New Horizons was roughly 6 million kilometers (3.7 million miles) away from the Pluto-Charon system. Most of the bright features along the edge of Pluto’s disk are artifacts from image processing, although the bright silver “whale” is a real feature. The image was blended with data collected by the Ralph instrument earlier in the mission to create a colour composite. The coolest bit about today’s image release is that we’re starting to finally see some of Charon’s surface features. Frustratingly, it looks like Charon doesn’t have many surface features for us to see!
Processed image of the Pluto-Charon system captured on July 8, 2015. Image credit: NASA/JHUAPL/SWRI
Most fascinatingly, Charon and Pluto are just starting to reveal that despite their similarities, they are distinctly different worlds. Pluto has an array of high-contrast features tinted to a distinctive red; Charon is covered in more uniform light grey terrain. Pluto has an atmosphere (at least, for this stage of its orbit) and layers of exotic ices including nitrogen, methane, and carbon monoxide; Charon lacks an atmosphere and contains just simple water and ammonia compounds. Where Pluto is a cold rock in deep space, Charon is composed of a near-equal mix of rock and ice.
Close-up of Charon imaged using the Long Range Reconnaissance Imager (LORRI) on July 8, 2015. Image credit: NASA/JHUALP/SWRI
At about half the diameter of Pluto, Charon is the largest moon relative to its parent in the solar system and noticeably yanks Pluto into orbiting around their center of mass. Yet, at only 1,200 kilometers (750 miles) across, its small size conspires with the low contrast of its surface features to thwart attempts to prying out its secrets. Squinting at first images are making the mission’s Geology, Geophysics and Imaging team (GGI) optimistic about the prospect of craters. If those blurry circular features resolve into crisp craters from, team leader Jeff Moore is fully prepared to make the most of their good fortune:
If we see impact craters on Charon, it will help us see what’s hidden beneath the surface. Large craters can excavate material from several miles down and reveal the composition of the interior.
Want to indulge in more Pluto-giddiness? Mission scientist Alex Parker created a banner for you to declare your love for the tiny red world perfectly sized for Facebook. You can use the free Pluto Safari app [iTunes; Google Play] to track the mission or explore the world in Google maps. Want to get more hands-on? Venture outside at your location’s Pluto Time to be surprised by just how bright it is at noon on the distant almost-planet. (And if you’re somewhere swathed in smoke from wildfires, you get the unintentional bonus of Pluto-red skies!)
Top image: The Pluto-Charon system imaged on July 8, 2015. Get an uncropped, high-resolution image here. Credit: NASA/JHUAPL/SWRI