When Jupiter was still forming 4.5 billion years ago, something giant probably crashed on the planet and interrupted the process, according to a new study.
NASA’s Juno spacecraft began orbiting Jupiter in July 2016. In addition to capturing stunning images of the gas giant, Juno also discovered a surprising view that only raises more questions.
According to the latest observations, Juno’s data on Jupiter’s gravity suggests that the planet does not have a small, dense nucleus as expected. Instead, there is a diluted core, researchers said. At first, they could not understand why.
“Instead of a small compact core as we assumed earlier, Jupiter’s core is ‘diffuse,'” said Ravit Helled, co-author of the study, member of the Juno mission team and professor at the University of Zurich. “This means that the core is probably not just made of rocks and ice, but also mixed with hydrogen and helium, and there is a gradual transition instead of an acute boundary between the core and the shell.”
But what could interrupt the core? It would require something that could shake the core. A giant impact seemed likely.
The international team of researchers used simulations of model collisions between the Jupiter that was still forming and the baby planets. Their results showed that a frontal collision between Jupiter and a young planet 10 times the mass of the Earth would have enough impact to destroy the nucleus. This would dilute it by allowing heavy metals to mix inside it.
“Because it is dense and comes with a lot of energy, the impactor would be like a bullet that cuts through the atmosphere and hits the nucleus head on,” said Andrea Isella, co-author of the study and astronomer at Rice University. “Before the impact, you have a very dense core, surrounded by atmosphere. The frontal impact extends things and dilutes the core. ”
The results of the study were published this week in the journal Nature .
The researchers also wanted to know if the diluted nucleus persisted for billions of years, or if it evolved that way over time.
“We are talking about very different time scales,” said Simon Müller, co-author of the study and PhD student at the University of Zurich, who performed the simulations of Jupiter’s evolution. “The giant impacts occurred early in the history of the solar system and lasted a short time, while evolution is a long process to date, 4.5 billion years after Jupiter’s formation.”
Their calculations showed that the diluted nucleus persisted, which has implications for more than Jupiter.
“That makes the case of the giant impact much stronger,” Helled said. “It seems that such violent impacts were very common in the young solar system and, curiously, they played an important role in the configuration of planetary characteristics, not only for Jupiter, as we suggest in this document, but also for other planets, to explain the Moon of the Earth, the high fraction of metal to rock in Mercury and the inclination of Uranus. ”