07/17/2015 11:50 EDT | Updated 07/17/2016 05:59 EDT

NASA releases more New Horizons photos of Pluto

NASA has released more images of Pluto, and theories, after the spacecraft New Horizons made its historic flyby of the dwarf planet earlier in the week.

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One photo is of a carbon monoxide-rich area within the Tombaugh Regio, Pluto's vast heart-shaped feature.

"There is no other carbon monoxide concentration like this, said Alan Stern, principal investigator of the New Horizons. "It's a very special place on the planet."

NASA released its first group of high-resolution images of the icy dwarf planet on Wednesday, a day after the flyby, showing mountains on Pluto and canyons on the largest of its five moons, Charon.

Some of the ice mountains on Pluto are comparable in size to some of the smaller Rocky Mountains. Charon's canyons may be up to nine kilometres deep.

The lack of craters on both Pluto and Charon suggests the two are still geologically active.

A closeup of the crater-free area named Sputnik Planum was released during Friday's briefing. Scientists believe Pluto's plains may be less than 100 million years ago.