Pluto

Pluto looks like a “large chewable malted ball.” Now, new images from New Horizons revealed a wide bite mark on the dwarf planet’s surface. How did that happen?
(Photo : NASA/JHUAPL/SwRI)

When the high-resolution image of Pluto came out last year, folks on the Internet said they thought the dwarf planet looked like a “big, icy malted ball.”

If you think about it, it does seem like the dwarf planet is chewable.

Now, a strange coincidence occurs: new high-res images sent by NASA’s New Horizons mission revealed that there is a wide “bite mark” on Pluto’s surface.

In fact, New Horizons detected the mark far in the dwarf planet’s western hemisphere, in the western plain informally called Piri Planitia.

Below Piri Planitia is Vega Terra, another informally named terrain with very old craters. Vega Terra is actually divided from the plains of Piri Planitia by a wall of cliffs or scarps called Piri Rupes.

Some of the scarps are broken off and have created isolated hills or mesas. You can see it in the image below.

(Photo: NASA/JHUAPL/SwRI)

Although it’s ridiculous to believe that a giant monster may have already taken a bite of Pluto’s “chocolate-ish” surface, NASA has a much more logical theory as to why the bite mark is there.

New Horizons scientists say the ridges may have been caused by sublimation, a process in which a solid substance transitions into gas. It’s also because of how ice in extreme environments reacts to being heated.

Pluto’s surface, which is rich in methane, may be sublimating away into the atmosphere as the planet receives the tiniest amount of heating. The process then exposed a layer of water ice underneath.

Discovery News compares it to a “rejuvenating facial scrub,” in which Pluto’s surface is gently heated by the distant sun. Ice layers are peeled away, allowing the creation of young-looking regions free of ancient impact craters.

Water ice at sea level temperatures on Earth will melt into liquid, then boil into vapor when heated. But on Pluto, because the temperatures are so cold and the pressure is almost vacuum-like, liquid water does not form and water ice will sublimate into vapor.

Additionally, New Horizons found that Piri Planitia’s surface is more enriched in water ice than other regions, indicating that the former is made of water ice bedrock. The water ice is rock-like and immobile, scientists said.

The compositional data was captured by New Horizons’ Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument.

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