Pluto’s iconic heart garnered widespread attention when NASA’s New Horizons flew past the dwarf planet. Scientists who further studied data from New Horizons probe have said that Pluto’s giant heart may have caused its entire body to tip over. Researchers at the University of Tuscon, Arizona said at the Lunar and Planetary Sciences Conference in Texas that dense frozen nitrogen in the region had changed the dwarf planet’s orientation.
Nitrogen ice build up changed Pluto orientation
The heart region is known as Tombaugh Regio. Scientists believe the west side of the heart, called Sputnik Planum, forms the remnants of a large crater that is now filled with nitrogen ice. Sputnik Planum is smooth, indicating it is less than 10 million years old. The dwarf planet rotates around the Sun such that its poles get most of the sunlight.
As a result, nitrogen and other gases condense on the shadowed regions of Pluto. As the dwarf planet goes around the sun, the frozen gases heat up to become gaseous again, and recondense on the other side. James Keane, who led the team, said some nitrogen accumulates in the crater every Pluto year. Over a long period of time, enough ice has piled up to overwhelm the dwarf planet’s orientation. Keane estimates the nitrogen ice built up is about one kilometer thick.
Sputnik Planum lining up with Charon no coincidence
When you have excess mass in one spot, it will likely move to the equator. It will tip the whole planet over, over a period of millions of years. Using data from New Horizons and computer simulations, scientists found that the heart region lines up well with the tidal axis of Pluto where the dwarf planet and its moon are linked together. The tidal axis is an imaginary line that indicates where the gravitational pull from the dwarf planet’s largest moon Charon is the strongest.
Pluto and Charon are tidally linked, always showing the same face to each other as they rotate. Scientists noticed that the center of the massive crater lies very close to the tidal axis. This can’t be a coincidence. If Sputnik Planum is denser than the rest of the dwarf planet, Charon’s gravitational pull on it will be significantly larger, causing the dwarf planet to swivel, said Keane.