This morning, however, I decided that I want to understand more about what the New Horizons mission has learned about Pluto. The images in this post were acquired from https://www.nasa.gov/mission_pages/newhorizons/images/index.html.
Pluto’s bright, mysterious “heart” is rotating into view, ready for its close-up on close approach, in this image taken by New Horizons on July 12 from a distance of 1.6 million miles (2.5 million kilometers).
The photo was taken about five hours before closest approach to Pluto, from a range of 150,000 miles (250,000 kilometers). The image highlights the contrasting appearance of the two worlds: Charon is mostly gray, -- with a dark reddish polar cap -- while Pluto shows a wide variety of subtle color variations, including yellowish patches on the north polar cap and subtly contrasting colors for the two halves of Pluto’s “heart”, now informally named Tombaugh Region, seen in the upper right quadrant of the image.
The above close up image shows a region near Pluto’s equator that reveals a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body.
The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system -- and may still be in the process of building. The mountains are probably composed of Pluto’s water-ice “bedrock.” Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. The close-up image was taken about 1.5 hours before New Horizons closest approach to Pluto, when the craft was 47,800 miles (77,000 kilometers) from the surface of the planet. The image easily resolves structures smaller than a mile across.
The image above shows a newly discovered mountain range that lies near the southwestern margin of Pluto’s Tombaugh Region, situated between bright, icy plains and dark, heavily-cratered terrain. This image was acquired on July 14, 2015 from a distance of 48,000 miles (77,000 kilometers). Features as small as a half-mile (1 kilometer) across are visible.
These newly-discovered frozen peaks are estimated to be one-half mile to one mile (1-1.5 kilometers) high, about the same height as the United States’ Appalachian Mountains. The Norgay Mountains discovered by New Horizons on July 15 more closely approximate the height of the taller Rocky Mountains.
“There is a pronounced difference in texture between the younger, frozen plains to the east and the dark, heavily-cratered terrain to the west,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team. “There’s a complex interaction going on between the bright and the dark materials that we’re still trying to understand.”
While Sputnik Planum is believed to be relatively young in geological terms – perhaps less than 100 million years old - the darker region probably dates back billions of years. Moore notes that the bright, sediment-like material appears to be filling in old craters (for example, the bright circular feature to the lower left of center).