According to a recent research from Lawrence Livermore National Laboratory (LLNL) in collaboration with University of Munster, Jupiter is not only the largest planet in the solar system but also the oldest. A group of researchers has found that Jupiter is the oldest planet in our solar system that came into existence within four million years after the formation of our solar system.
By looking at tungsten and molybdenum isotopes on iron meteorites, the team found that meteorites are made up of two distinct nebular reservoirs that coexisted but remained separated between 1 million to 3-4 million years after the formation of our solar system. The most plausible mechanism for this efficient separation is the formation of Jupiter, opening a gap in the disc (a plane of gas and dust from stars) and preventing the exchange of material between the two reservoirs,” said Thomas Kruijer, scientist from LLNL and lead author of the paper that has been published in an online issue of Proceedings of the National Academy of Sciences. Other authors include Christoph Burkhardt, Gerrit Budde and Thorsten Kleine of the University of Munster.
“Jupiter is the oldest planets in the solar system, and its solid core formed well before the solar nebula gas dissipated, consistent with the core accretion model for giant planet formation,” added Thomas Kruijer.
Knowing the age of Jupiter is key to understanding how the solar system evolved toward its present-day architecture. Although models predict that Jupiter formed relatively early, until now, its formation has never been dated.
“We do not have any samples from Jupiter, in contrast to other bodies like the Earth, Mars, the moon and asteroids,” said Kruijer. “In our study, we use isotope signatures of meteorites to infer Jupiter’s age.”
Through some isotope analysis of meteorites, the researchers showed that Jupiter’s solid core formed within only about 1 million years after the start of the solar system history, making it the oldest planet.
Through its rapid formation, the gas giant acted as an effective barrier against inward transport of material across the disc, potentially explaining why our solar system lacks any super-Earths (an extrasolar planet having mass higher than Earth).
Jupiter’s core grew to about 20 Earth masses within 1 million years, followed by a more prolonged growth to 50 Earth masses until at least 3-4 million years after the solar system formed.
As per the earlier theories, planets like Jupiter and Saturn involved the growth of large solid cores of about 10 to 20 Earth masses, followed by the accumulation of gas onto these cores. The theory concluded that the gas giant cores must have formed before dissipation of the solar nebula (the gaseous circumstellar disc surrounding the young sun) which likely occurred between 1 million years and 10 million years after the solar system formed.
Confirming the earlier theories, the team of scientists were able to date Jupiter much more precisely within 1 million years using the isotopic signatures of meteorites. “Our measurements show that the growth of Jupiter can be dated using the distinct genetic heritage and formation times of meteorites,” stated Kruijer.