One of the coolest things about Pluto that was shown in the images sent back by the New Horizons probe is the heart-shaped area on the surface dubbed Tombaugh Regio. Scientists have been researching the data gathered by New Horizons and the study is now suggesting that the heart-shaped area might be heavy enough to have tipped the dwarf planet on its side. The west side of the heart called Sputnik Planum with its smooth surface is through to be what remains of a large crater that filled with nitrogen ice.
Scientists say the west side of the area is smooth and crater free because it is less than 10 million years old, making it very fresh on a cosmic scale. The massive crater is close to the tidal axis of the dwarf planet where the moon Charon and Pluto are linked together. Pluto and its moon are tidally linked with the same faces showing as they rotate.
Scientists think that the remains of the crater and Charon lining up so well isn’t a coincidence. Two teams of scientists investigating the data gathered by New Horizons think that if Sputnik Planum is denser than the rest of Pluto on average that the gravitational tug Charon exhibits on it would also be greater, possibly causing the entire dwarf planet to swivel. The increased density in the crater is thought to be due to the massive amount of nitrogen ice that has built up over time.
The ice in that region is believed to be about a kilometer thick. The researchers created models of the dwarf planet and believe that the heart could have been centered north or north-west of its current location. If true that would mean the planet has swiveled as much as hundreds or thousands of kilometers over millions of years. Another team thinks that a subsurface ocean could account for the swiveling of the planet over millions of years.
SOURCE: New Scientist