New Horizons reveals striking features on Charon
Charon has got its turn in New Horizons’ spotlight on July 11, with its latest images showing striking features, revealing the large moon to be a geologically active world. Its surface is pockmarked with chasms and craters, evidence that the small world has undergone faulting and surface disruption, according to Geology and Geophysics Investigation team (GGI) deputy lead scientist William McKinnon of Washington University at St.Louis.
The miniature world’s most prominent crater, located in its southern hemisphere near the south pole, is much longer and deeper than the Grand Canyon on Earth; it is estimated to be 60 miles (96.5 km) across. Rays of material ejected from the crater appear bright, meaning it formed in the last billion years when the moon was impacted by a Kuiper Belt Object (KBO).
“New Horizons has transformed our view of this distant moon from a nearly featureless ball of ice to a world displaying all kinds of geologic activity,” McKinnon emphasized.
He is especially interested in the crater’s dark floor, which may be composed of a different type of ice than the brighter, more reflective surface.
Alternatively, the ice at the bottom of the crater could be made up of the same material as that on the surface, but the individual ice grains at the bottom are larger than those on top. The impacting of a Kuiper Belt Object could have initially melted the ice at the crater’s bottom. That ice then might have frozen back in larger individual grains. Larger grains reflect less sunlight, which could explain why the bottom of the crater is darker.
There is also a strange, dark feature about 200 miles long near Charon’s north pole, which New Horizons will image in more detail during its July 14 flyby.
The New Horizons spacecraft also took images of Pluto on July 11, which revealed linear and circular features that could be cliffs and craters, respectively.
For the first time on Pluto, these views reveal linear features that may be cliffs, as well as a circular feature that could be an impact crater. The above images show the intriguing, bright heart-shaped feature rotating back into view on the left of the disk, and it will be imaged closely on the July 14 flyby.
Last night, Sunday, July 12, at 11:23 p.m. EDT (03:23 GMT on July 13), the New Horizons spacecraft past its “one million miles to go” milestone.
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.