Scientists reveal the origin of Pluto's “heart”.

Scientists discovered that the collision was slow and hit an area covered by 730 kilometers of ice. Three mathematical simulations were performed to reach this conclusion. “We are used to thinking of planetary collisions as incredibly intense events (…) but in the distant solar system, the speeds are much slower and the solid ice is strong,” says Eric Asvog, one of the researchers.

The impact likely occurred at a steep angle rather than directly. According to the research, the impact occurred at an angle of 30 degrees. “Pluto's core is so cold that the rocks remained very solid and did not melt despite the heat of the impact, and thanks to the impact angle and low speed, the core of the impacting object did not sink into Pluto's core but remained intact as a spray of water.” explains Harry Ballantyne, one of the researchers.

The “heart” is also known as the Tombo area. The name is an homage to astronomer Clyde Tombaugh, who discovered Pluto in 1930. The western part of the core – which forms a teardrop – is known as Sputnik Planitia. Pluto's average surface temperature can reach -230 degrees Celsius.

The research concluded that there is no underground ocean on Pluto as previously thought. “The formation of Sputnik Planitia provides an important window into the early periods of Pluto’s history,” says researcher Adeney Denton.