Jupiter is oldest planet in solar system, ancient meteorites show By Ben Guarino June 12 at 3:00 PM
When the solar system was about 1 million years old, Jupiter's gravity was strong enough to prevent rocks from crossing beyond its orbit. Here the planet is seen through a Hubble telescope image. (A. Simon via GSFC/NASA/ESA)Jupiter formed in a geologic blink. Its rocky core coalesced less than a million years after the beginning of our solar system, scientists reported Monday in the
Proceedings of the National Academy of Sciences. Within another 2 million or 3 million years, that core grew to 50 times the mass of Earth.
Scientists have previously built computer models of the birth of Jupiter. But this study “is the first time that we can say something about Jupiter based on measurements done in the lab,” said study co-author
Thomas S. Kruijer, a researcher at the Lawrence Livermore National Laboratory in California.
To probe the planet's creation, experts sampled extraterrestrial material that happens to land on Earth — ancient meteorites.
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But Kruijer and his colleagues can measure specific chemical signatures in meteorites — which reveal not only the rocks' age but which of the two groups they once belonged to. It was only recently that technological advances allowed scientists to measure the differences in the two, Kruijer said.
The meteorite groups separated around 1 million years after the solar system formed, and stayed apart until about 4 million years post-formation, according to the new analysis. Crucially, the two populations existed simultaneously for a few million years.
“It cannot be a temporal change. It must be a spatial separation,” Kruijer said. Something must have kept them apart. The most likely culprit, the authors of the study say, is a young Jupiter. “It's hard to think of any other possibility,” he said.
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https://www.washingtonpost.com/news/speaking-of-science/wp/2017/06/12/jupiter-is-oldest-planet-in-solar-system-ancient-meteorites-show/
