New Horizons sees Pluto’s close approach hemisphere and Charon’s ‘dark pole’

These images, taken by New Horizons' Long Range Reconnaissance Imager (LORRI), show numerous large-scale features on Pluto's surface. The distance to Pluto ranges from 47 million kilometres (about 29 million miles) on June 5 to 31 million kilometres (19 million miles) on June 18. When various large, dark and bright regions appear near limbs, they give Pluto a distinct, but false, non-spherical appearance. Pluto is known to be almost perfectly spherical from previous data. These images are displayed at four times the native LORRI image size, and have been processed using a method called deconvolution, which sharpens the original images to enhance features on Pluto. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. — These images, taken by New Horizons’ Long Range Reconnaissance Imager (LORRI), show numerous large-scale features on Pluto’s surface. The distance to Pluto ranges from 47 million kilometres (about 29 million miles) on June 5 to 31 million kilometres (19 million miles) on June 18. When various large, dark and bright regions appear near limbs, they give Pluto a distinct, but false, non-spherical appearance. Pluto is known to be almost perfectly spherical from previous data. These images are displayed at four times the native LORRI image size, and have been processed using a method called deconvolution, which sharpens the original images to enhance features on Pluto. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

In a long series of images obtained by New Horizons’ telescopic Long Range Reconnaissance Imager (LORRI) between May 29 and June 19, Pluto and its largest moon, Charon, appear to more than double in size. From this rapidly improving imagery, scientists on the New Horizons team have found that the “close approach hemisphere” on Pluto that New Horizons will fly over has the greatest variety of terrain types seen on the planet so far. They have also discovered that Charon has a “dark pole” — a mysterious dark region that forms a kind of anti-polar cap.

“This system is just amazing,” said Alan Stern, New Horizons Principal Investigator, from the Southwest Research Institute, Boulder, Colorado. “The science team is just ecstatic with what we see on Pluto’s close approach hemisphere: Every terrain type we see on the planet — including both the brightest and darkest surface areas — are represented there, it’s a wonderland!

“And about Charon — wow — I don’t think anyone expected Charon to reveal a mystery like dark terrains at its pole,” he continued. “Who ordered that?”

These recent images show the discovery of significant surface details on Pluto’s largest moon, Charon. They were taken by the New Horizons Long Range Reconnaissance Imager (LORRI) on June 18, 2015. The image on the left is the original image, displayed at four times the native LORRI image size. After applying a technique that sharpens an image called deconvolution, details become visible on Charon, including a distinct dark pole. Deconvolution can occasionally introduce "false" details, so the finest details in these pictures will need to be confirmed by images taken from closer range in the next few weeks. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. — These recent images show the discovery of significant surface details on Pluto’s largest moon, Charon. They were taken by the New Horizons Long Range Reconnaissance Imager (LORRI) on June 18, 2015. The image on the left is the original image, displayed at four times the native LORRI image size. After applying a technique that sharpens an image called deconvolution, details become visible on Charon, including a distinct dark pole. Deconvolution can occasionally introduce “false” details, so the finest details in these pictures will need to be confirmed by images taken from closer range in the next few weeks. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

“The unambiguous detection of bright and dark terrain units on both Pluto and Charon indicates a wide range of diverse landscapes across the pair,” said science team co-investigator and imaging lead Jeff Moore, of NASA Ames Research Center, Mountain View, California. “For example, the bright fringe we see on Pluto may represent frost deposited from an evaporating polar cap, which is now in summer sun.”

In a related press release, the first colour movies from New Horizons show the complex orbital dance of Pluto and Charon.

This near-true colour movie of Pluto and largest moon Charon was assembled from images made in three colours — blue, red and near-infrared — by New Horizon's Multicolor Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29 to June 3, 2015. The movie is barycentric, meaning that both Pluto and Charon are shown in motion around the binary's barycentre — the shared centre of gravity between the two bodies as they do a planetary jig. Because Pluto is much more massive than Charon, the barycentre (marked by a small "x" in the movie) is much closer to Pluto than to Charon. 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. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. — This near-true colour movie of Pluto and largest moon Charon was assembled from images made in three colours — blue, red and near-infrared — by New Horizon’s Multicolor Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29 to June 3, 2015. The movie is barycentric, meaning that both Pluto and Charon are shown in motion around the binary’s barycentre — the shared centre of gravity between the two bodies as they do a planetary jig. Because Pluto is much more massive than Charon, the barycentre (marked by a small “x” in the movie) is much closer to Pluto than to Charon. 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. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

“It’s exciting to see Pluto and Charon in motion and in colour,” says Alan Stern. “Even at this low resolution, we can see that Pluto and Charon have different colours — Pluto is beige-orange, while Charon is grey. Exactly why they are so different is the subject of debate.”

As New Horizons closes in its intended target, the best is yet to come. “Colour observations are going to get much, much better, eventually resolving the surfaces of Charon and Pluto at scales of just kilometres,” said Cathy Olkin, New Horizons deputy project scientist from SwRI. “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!”

New Horizons is approximately 2.9 billion miles (4.7 billion kilometres) from Earth and just 16 million miles (25 million kilometres) from Pluto. The spacecraft and payload are in good health and operating normally.

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