Scientists studying Jupiter have been trying to figure out why the planet has such strange gravitational readings. The readings suggest to scientists that the core of the planet is much less dense and more extended than expected. Scientists now have a theory on what caused the strange readings for the planet.
Astronomers from Rice University and China’s Sun Yat-sen University believe that Jupiter and a still-forming planet collided head-on about 4.5 billion years ago. The collision theory would explain the oddities in Jupiter’s gravitational measurements. The leading theories on planet formation suggest that Jupiter started as a dense, rocky or icy planet that later gathered the thick atmosphere from a primordial disk of gas and dust that birthed the sun.
Rice astronomer Andrea Isella says that she was skeptical when Shang-Fei Liu first suggested the head-on collision theory could explain some of the mysteries of Jupiter. Isella says that the theory sounded unlikely to him, but that Shang-Fei convinced him using calculations that a collision was not improbable.
After running thousands of computer simulations, the team found that a fast-growing Jupiter could have disturbed the orbits of nearby planets in the early stages of formation. The simulations showed a 40% chance that Jupiter would collide with a planetary embryo in its first few million years.
The team says that the strong gravitational forces of Jupiter also made a head-on collision more likely than a grazing collision. Additional 3D computer models that showed how such a collision would affect Jupiter’s core made a collision scenario more compelling. The team says that the only scenario that resulted in a core-density profile similar to what Juno has measured was a head-on impact with a planetary embryo about ten times more massive than Earth.