A new study found that Jupiter is not only the largest planet in our solar system but the oldest too. This is the first study that dates Jupiter’s age, which, according to the researchers, is around 4.5 billion years old.
The researchers looked at the composition of iron meteorites and found that Jupiter’s solid core was formed around one million years after the solar system created 4.6 billion years ago.
The researchers from Lawrence Livermore National Laboratory and Institut für Planetologie at the University of Münsterin Germany hope that the findings will provide important insight into how the solar system evolved into its current formation. The study was published Monday in the journal Proceedings of the National Academy of Sciences.
Scientists looked at iron meteorites and found Jupiter’s actual age: 4.5 billion years old
A previous study had created models, which predicted that Jupiter formed relatively early. However, the new study, led by the Lawrence Livermore National Laboratory in California, is the first ever to date its exact formation.
“We do not have any samples from Jupiter (in contrast to other bodies like the Earth, Mars, the moon and asteroids),” said Dr. Thomas Kruijer, lead author of the study and scientist at the Lawrence Livermore National Laboratory, according to Daily Mail. “In our study, we use isotope signatures of meteorites (which are derived from asteroids) to infer Jupiter’s age.”
The international team of researchers found that meteorites are made up from two genetically distinct reservoirs of gas and dust that once co-existed, but remained separated, sometime between one million and four million years after the solar system formed.
Dr. Kruijer noted that the most plausible mechanism for that efficient separation is the formation of Jupiter, opening a gap in the disc, which is a plane of gas and dust from stars- and preventing the exchange of material between the two reservoirs.
“Jupiter is the oldest planet of 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,” said Dr. Kruijer, according to Phys.org.
Jupiter grew over 20 Earth masses in one million years, and then it grew 50 more masses
For years it has been known that Jupiter is the largest planet in the solar system, and according to the study, its presence had a big effect on the dynamics of the solar accretion disk. Knowing with certainty the age of Jupiter will be essential for studying how the solar system has evolved.
The researchers showed through isotope analyses of meteorites that the planet’s solid core formed within about 1 million years after the formation of the solar system. Through its quick formation, Jupiter acted as an efficient and powerful barrier against inward transport of material across the disk, which potentially explains why our solar system does not have any super-Earths, which are extrasolar planets with a mass higher than Earth’s.
The study also explained that Jupiter’s core grew to about 20 Earth masses within only one million years, followed by a more paced growth to 50 Earth masses until at least 3 to 4 million years after the solar system formed.
The previous hypotheses proposed that gas giants like Jupiter and Saturn involved the growth of major solid cores of around 10 to 20 Earth masses, which was followed by the accumulation of gas onto these large cores. Meaning, scientists believed that the gas-giant cores must have been created before dissipation of the solar nebula (the gaseous circumstellar disk that surrounded the young sun) which likely must have occurred between 1 million years and 10 million years after our solar system formed.
Researchers were able to date Jupiter’s formation within 1 million years
In the new study, the researchers confirmed the initial hypotheses, but they were also able to date Jupiter much more precisely within 1 million years through the method of measuring isotopic signatures of meteorites. The team noted that although this rapid accretion of the cores has been modeled, it had not been possible to date their formation until now.
“Our measurement show that the growth of Jupiter can be dated using the distinct genetic heritage and formation times of meteorites,” said Kruijer, according to Phys.org.
Most meteorites come from small bodies that are located in the main asteroid belt between Jupiter and Mars. Scientists believe that initially these bodies probably formed at a much wider range of heliocentric distances. This is suggested by the distinct chemical and isotopic compositions of meteorites and also by the dynamical models that indicate that the gravitational influence of the gas giants such as Jupiter and Saturn, led to the scattering of small bodies into the asteroid belt.