Astronomers have finally figure out how old Jupiter is. According to a recent study, the gas giant's main core had already grown to be 20 times more massive than Earth just 1 million years after the sun formed. Lead author of this study, Thomas Kruijer, of the University of Munster in Germany and Lawrence Livermore National Laboratory in California, said in a statement:
"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,"
Some 4.6 billion years ago, the solar system coalesced from an enormous cloud of gas and dust. The sun formed first, and the planets then accreted from the leftover material spinning around the newborn star in a vast disc. Theoretical work powerfully proposes that Jupiter took form pretty early in the solar system's history, but the planet's exact age had persisted as a mystery among astronomers.
The astronomers predicted Jupiter's formation and evolution by examining the ages of definite iron meteorites — remains of the metallic cores of earliest planetary building blocks — that have crashed on Earth. These ages were outlined by measuring the richness of molybdenum and tungsten isotopes.
This work specified that the meteorites originated from two separate "reservoirs" that were spatially distinct for 2 million to 3 million years, starting about 1 million years after the solar system formed, the researchers said. The scientists said in the new study, which was issued online today (June 12) in the journal Proceedings of the National Academy of Sciences.
"The most plausible mechanism for this efficient separation is the formation of Jupiter, opening a gap in the disk and preventing the exchange of material between the two reservoirs,"
Jupiter's core would have to be about 20 times more immense than Earth to keep the two reservoirs from mingling, Kruijer and his group calculated. So, the outcomes proposed the emerging gas giant was already that big inside the first 1 million years of solar system history, the researchers said.
Jupiter's evolution rate decelerated afterwards, they said. The gas giant didn't stretch to 50 Earth masses until a least of 3 million to 4 million years after the sun's formation, the scientists determined.
Kruijer said in the same statement:
"Our measurements show that the growth of Jupiter can be dated using the distinct genetic heritage and formation times of meteorites,"
The recent study could also assist explaining why the solar system lacks worlds midway in mass between Earth and "ice giants" such as Uranus and Neptune. Such "super-Earths" are fairly common in other star systems.
The researchers wrote in the new study:
"One important implication of this result is that, because Jupiter acted as a barrier against inward transport of solids across the disk, the inner solar system remained relatively mass deficient, possibly explaining its lack of any 'super-Earths,’”