Juno, the NASA probe orbiting Jupiter since 2016, has been sending back information that are giving scientists new insights into the evolution and structure of the planet. One new study suggests that 4.5 billion years ago, when the Solar System was still young, Jupiter received a massive whack from a planet still being formed, and swallowed it up. Another study looks at the reasons why the “stripes” on Jupiter do not run deep into its surface.
Collision with a proto-planet
Information sent by Juno shows that Jupiter’s core is not mainly ice and rock as previously thought, but a “fuzzy core” that includes lighter elements like helium and hydrogen. This, scientists suggest in the journal Nature, could be explained by a head-on collision with a still-forming planet about 10 times the size of Earth.
Researchers from Rice University in the US and Sun Yat-sen University in China worked on the idea that a colossal event stirred up Jupiter’s core, diluting it. Computer simulations suggested a growing Jupiter could have disturbed the orbits of nearby “planetary embryos”, and that there was at least a 40% chance that Jupiter would swallow a planetary embryo within its first few million years, Rice University said in a statement.
Skin deep stripes
There is a reason why Jupiter’s stripes are only skin deep, the Lawrence Livermore National Laboratory (LLNL) of the US said in a statement. A team looked to the Juno mission that revealed how far zonal winds around Jupiter descend — to a depth about 4 percent of Jupiter’s radius.
It is these zonal winds — alternating east-west jet streams — that are seen in photographs as colourful stripes on Jupiter. In a paper in Physical Review Fluids, researchers have shown that these zonal winds can only descend to 3,000 km in the atmosphere.
Magnetic fields can make fluids that conduct electricity (like Jupiter’s atmosphere) behave more like honey than water. Deeper into the planet, where the pressure is higher, the atmosphere becomes more conducting and is more strongly influenced by the planetary magnetic field. It’s also the same place where the stripes stop, LLNL explained.