Ice gave Pluto a heavy heart | Science News

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Ice gave Pluto a heavy heart

Buildup of frozen deposits could have carved dwarf planet’s iconic landscape

By
1:00pm, November 30, 2016
Sputnik Planitia

FEELING DOWN  A basin on Pluto named Sputnik Planitia (at right in this image from New Horizons) might be a depression formed by the weight of a massive ice cap, a new study suggests.

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Pluto’s heart might carry a heavy burden.

Weight from massive deposits of frozen nitrogen, methane and carbon monoxide, built up billions of years ago, could have carved out the left half of the dwarf planet’s heart-shaped landscape, researchers report online November 30 in Nature.

The roughly 1,000-kilometer-wide frozen basin dubbed Sputnik Planitia was on display when the New Horizons spacecraft tore past in July 2015 (SN: 12/26/15, p. 16). Previous studies have proposed that the region could be a scar left by an impact with interplanetary debris (SN: 12/12/15, p. 10).

Sputnik Planitia sits in a cold zone, a prime location for ice to build up, planetary scientist Douglas Hamilton of the University of Maryland in College Park and colleagues calculate. Excess ice deposited early in the planet’s history would have led to a surplus of mass. Gravitational interactions between Pluto and its largest moon, Charon, slowed the planet’s rotation until that mass faced in the opposite direction from Charon. Once Charon became synced to Pluto’s rotation — it’s always over the same spot on Pluto — gravity would have held Sputnik Planitia in Pluto’s cold zone, attracting even more ice. As the ice cap grew, the weight could have depressed Pluto’s surface, creating the basin that exists today.

Citations

D.P. Hamilton et al. The rapid formation of Sputnik Planitia early in Pluto’s history. Nature. Published online November 30, 2016. doi: 10.1038/nature20586. 

Further Reading

C. Crockett. A salty sea could lurk beneath the heart of Pluto. Science News Online, September 23, 2016.

C. Crockett. Year in review: Pluto unveiled as a world like no other. Science News. Vol. 188, December 26, 2015, p. 16.

C. Crockett. Impact from a space rock may have helped shape Pluto’s heart. Science News. Vol. 188, December 12, 2015, p. 10.

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