Astronomer at the Southwest Research Institute in Boulder, Colorado (USA), David Nesvorny, proposes that a group of icy bodies in the same area as Pluto could be proof that our early solar system was home to a fifth giant planet . The study has been published in The Astronomical Journal .
This fifth planet could have struck the planet Neptune 4 million years ago , causing it to jump out of its current orbit and also lead to the dispersal of a group of its satellites in the Kuiper belt (the set of comet bodies that orbit around the Sun at a distance of between 30 and 100 astronomical units). This would explain the presence of about a thousand icy rocks that have long been a mystery to scientists .
They represent an enigma because these icy rocks, unlike other icy bodies in the Kuiper belt, never move from the same orbital plane as the planets and tend to be and move together . Previously, astronomers had theorized that tightly knit objects formed from violent collisions of larger objects.
Now, thanks to various computer simulations to track the movements of these icy rocks around 4 million years ago, they discovered that the objects had been dragged by Neptune’s gravitational field when the planet migrated away from the sun . According to Nesvorny, the sudden change in Neptune’s orbit could have been caused by the gravitational influence of another object, probably a giant planet; but it could not be Uranus, Saturn or Jupiter since their orbits would never have interacted with Neptune in the way this proposed planet would have.
Where did this giant planet go? According to Nesvorny, trying to find out is not that simple. “The Kuiper belt is the key. Seeing the structures there and trying to figure out what kind of evolution would fit those structures, ”explains Nesvorny.
