It turns out the largest planet of our Solar System – Jupiter – is also the oldest with a team of scientists identifying the precise age of the gaseous giant using meteorites.
Scientists at University of Münster worked with those from Lawrence Livermore National Laboratory in California to determine a precise age of Jupiter using meteorites, fragments of asteroids that today reside in a belt between Mars and Jupiter. Specifically speaking, the team used isotope measurements to show that the asteroids originally derive from two distinct regions of the Solar System, one within and the other beyond the orbit of Jupiter.
Scientists used the isotopic compositions of the meteorites as a genetic fingerprint to deduce the relationships between different meteorites. By determining the age of meteorites, scientists showed that asteroids from inside and outside Jupiter’s orbit formed between one and four million years after Solar System formation.
This was a period when there was no material exchange between the two regions, scientists explain and this lack of mixing effectively means that once Jupiter reached about 20 Earth masses, it prevented material exchange across its orbit.
Once that core had formed, the growth of Jupiter continued through accretion of gas. This process was relatively slow initially until Jupiter reached a mass of about 50 Earth masses. The researchers were able to determine that point in time, because once Jupiter reached 50 Earth masses it started to scatter material from beyond its orbit into the inner Solar System.
The rapid growth of Jupiter has far-reaching implications for understanding the early history of the Solar System and the formation of the four inner (terrestrial) planets Mercury, Venus, Earth and Mars, the researchers say. Jupiter’s growth led to scattering of water-rich asteroids into the inner Solar System, where these bodies may have been incorporated into the Earth.
As such, water-rich asteroids are likely candidates for the source of water on Earth. But the rapid growth of Jupiter also inhibited significant mass transport into the inner Solar System, potentially explaining why Mars is so small and also why our Solar System, in contrast to many extrasolar systems, has no super-Earths (that is, large terrestrial planets).