The mystery surrounding the formation of the heart of the dwarf planet Pluto, clearly visible in images taken by the New Horizons probe, has finally been elucidated by an international team of astrophysicists. This discovery was made possible thanks to numerical simulations which successfully reproduced the unusual shape of this ice structure and attributed its origin to a giant, slow impact at an oblique angle.
A heart in the Kuiper belt
Sputnik Planitia, also known as the Sputnik Plain, is a remarkable region located on the surface of the dwarf planet Pluto. First identified in 2015 by NASA's New Horizons mission which provided the first detailed images of Pluto and its moons, it is distinguished by its heart shape and remarkably smooth appearance. It is also notably lower in altitude than the surrounding areas of the dwarf planet's surface with a depression reaching three to four kilometers. Finally, it mainly consists of nitrogen icewhich gives it a shiny, white appearance.
The exact origin of Sputnik Planitia is subject to debate, and has attracted the interest and attention of astronomers since its discovery. However, a leading theory suggests that it was the result of a cataclysmic collision in Pluto's distant past. According to this theory, a massive impactor struck Pluto's surface, forming the depression and leaving behind this characteristic shape. Numerical simulations also supported this hypothesis, revealing that the impact was oblique, thus explaining the elongated shape of Sputnik Planitia.
Recent research carried out by a team from the University of Bern and the University of Arizona in Tucson has shed some light on this.
A giant impact
According to this research, Sputnik Planitia was the result of a cataclysmic collision between Pluto and a planetary body of considerable size, estimated at approximately 700 kilometers in diameter. To put this into perspective, this planetary body would be about twice the size of Switzerland.
-One of the most significant findings from the numerical simulations is that the impact that formed Sputnik Planitia was oblique. As a reminder, during an oblique collision, the impactor does not strike the surface perpendicularly, but with a certain inclination. This means that the energy of the impact is unevenly distributed on the planet's surface, creating different forces and pressures depending on the direction of impact. As a result, the deformation of the planet's surface is not uniform, which can lead to the formation of complex geological structures. In the case of Sputnik Planitia, the oblique impact resulted in the creation of a elongated depression, which resembles the shape of a heart when viewed from above.
This discovery thus opens new perspectives on our understanding of the origin of Pluto and the formation of planets in the outer Solar System. Next steps in the research include further study of the migration of Sputnik Planitia and the impact on Pluto's internal structure.
An enigma solved thanks to international scientific collaboration
Elucidating the origin of Sputnik Planitia is the result of an unprecedented collaboration between researchers from several countries, combining space observations, advanced numerical simulations and geophysical modeling. This multidisciplinary approach made it possible not only to confirm the oblique impact theory, but also to explore the long-term repercussions of this event on the geological and thermal evolution of Pluto. This work illustrates the importance of collective efforts to answer major scientific questions and marks a key milestone in the study of icy bodies in the Kuiper Belt.
Details of the study are published in the journal Nature Astronomy.
