Juno reveals young Jupiter hit by planet 10 TIMES heavier than Earth

Pablo Tucker
August 16, 2019

It appears that, rather than a very dense central core with less-dense surroundings, the planet's core might actually be more diffuse, but with lots of heavy elements.

Jupiter has always been hailed as the mighty "king of planets" thanks to its massive size compared to most of the other planets in our solar system.

"Now, scientists have proposed an Almost-apocalyptic reason behind this: "A" planetary embryo" with 10 times greater mass than Earth (and nearly as much mass as Uranus) could have slammed in the largest planet in the solar system and disturbed its heart. What we'd typically expect - and this is true for both rocky planets and gas giants - is layers of increasing density, with the densest material packed at the center of the planet, where temperatures are hottest.

Initially, Isella was skeptical of this idea when it was put forward by lead author of the study Shange-Fei Liu from Sun Yat-sen University in China-a former postdoctoral researcher at Rice.

Prior to NASA's recent Juno mission, researchers assumed that Jupiter's core was a solid pit of rock and ice-a dense seed that was able to attract clouds of hydrogen and helium with its gravitational pull.

The only way to create conditions sufficient to lead to the gravitational distribution of material that we see is to smash Jupiter's core with an impactor of almost equivalent mass (to the core, not the entire planet), with a great deal of energetic mixing occurring thereafter. As a result, the diameter of Jupiter's core more than doubled. "It suggests that something happened that stirred up the core, and that's where the giant impact comes into play".

They also tested the theory that Jupiter's fragmented nucleus was caused by weather erosion or the possibility that it always contained core gas. A similar event might have been responsible for some unexpected properties of Jupiter's core, which seems strangely low-density yet high in heavy elements.

"It sounded very unlikely to me", Isella recalled, adding that it was "like a one-in-a-trillion probability".

The collision scenario became even more compelling after Liu ran 3D computer models that showed how a collision would affect Jupiter's core.

According to Liu, smaller planetary embryos about as big as Earth would break apart in Jupiter's thick atmosphere.

Liu said tens of thousands of computer simulations indicated at least a 40% chance that Jupiter was hit by a protoplanet early in its history, with this impact scenario offering "by far the best explanation" for the nature of Jupiter's core.

A rendering shows the effect of a major impact on the core of a young Jupiter, as suggested by scientists at Rice and Sun Yat-sen universities. Along with the stunning pictures Juno has sent back, it's also used its instruments to gaze deep into Jupiter's heart.

The Juno spacecraft, which launched in 2011, was created to help scientists better understand Jupiter's origin and evolution.

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