February 29, 2016 | David F. Coppedge

Pluto, Charon Details Trickle In

New photos from Pluto and Charon continue to show enigmatic features.

Pluto’s North Pole

Astrobiology Magazine posted a very detailed, color-enhanced image taken by New Horizons of the northern regions of Pluto, where deep canyons rival the largest in the solar system. One canyon is estimated to be 45 miles across; two others are six miles across. Click the image on the New Horizons page to appreciate the beauty of the full-resolution image.

Pluto north pole

Pluto’s north polar region
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Also puzzling are pits 45 miles across and 2.5 miles deep, seen at the lower right.

Large, irregularly-shaped pits reach 45 miles (70 kilometers) across and 2.5 miles (4 kilometers) deep, scarring the region. These pits may indicate locations where subsurface ice has melted or sublimated from below, causing the ground to collapse.

The color and composition of this region – shown in enhanced color – also are unusual.  High elevations show up in a distinctive yellow, not seen elsewhere on Pluto.  The yellowish terrain fades to a uniform bluish gray at lower elevations and latitudes. New Horizons’ infrared measurements show methane ice is abundant across Lowell Regio, and there is relatively little nitrogen ice.  “One possibility is that the yellow terrains may correspond to older methane deposits that have been more processed by solar radiation than the bluer terrain,” said Will Grundy, New Horizons composition team lead from Lowell Observatory, Flagstaff, Arizona.

Geology enthusiasts will appreciate a preliminary geology map constructed by the team showing features on the smooth region called Sputnik Planum.

Charon, Nitrogen Thief

A freezing ocean that apparently swelled and cracked the crust of Pluto’s large moon Charon has been compared by Space.com and the New Horizons team to the Incredible Hulk busting through his shirt. And if Pluto’s canyon’s are impressive, consider the odd finding that this moon, just a fourth the diameter of its parent, sports a canyon 1,100 miles long and 4.5 miles deep.

Another post on Space.com provides background information about Charon, including how it got its name. The little moon steals material from Pluto’s atmosphere:

New Horizons revealed an unusual feature, a surprising red formation at Charon’s northern pole. This reddish hue comes from Pluto’s atmosphere. Pluto itself is too small to hold onto its atmosphere for its lifetime, so the nitrogen, methane and carbon monoxide leave the surface. Close-orbiting Charon captures some of the material, which is then funneled toward the surface. As the material collects, galactic cosmic rays and ultraviolet light from the sun interact to create tholins, complex compounds that form through the irradiation of simple organic compounds.

Both Pluto and Charon may have had liquid oceans under their crusts, the article says.

Next Stop for New Horizons

The New Horizons team has selected a Kuiper Belt Object named 2014 MU69 for its next encounter. If all goes well, the spacecraft will buzz by this small object in January 2019. It’s only a fuzzy speck from Earth. Depending on its surface brightness, 2014 MU69 could be just 1% the size of Pluto.

History in the making! These are exciting times to watch new discoveries come in from distant parts of the solar system. Stay tuned for more surprises as data from the Pluto flyby continue to trickle in over the next few months.



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  • John C says:

    Interesting always, David. Would the presence of the Pluto dust only in the polar region be indicative of magnetic influences on Charon? Field activity, perhaps, similar to Earth’s?

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