In 2016, NASA’s Juno spacecraft arrived at Jupiter with the goal of peering through Jupiter’s dense clouds to reveal the giant planet’s inner secrets. Along with the stunning pictures Juno has sent back, it’s also used its instruments to gaze deep into Jupiter’s heart.
One of the spacecraft’s biggest discoveries was a core less compact than scientists expected. Instead of a sharp transition between a dense core and the more gaseous outer layers, Juno’s readings imply a fuzzy boundary, with the core bleeding into the atmosphere out to nearly half the planet’s radius.
Now, astronomers led by Shang-Fei Liu from Sun Yat-sen University in China have put forward an explanation for that fuzzy core: the young proto-Jupiter was involved in a head-on collision with a large proto-planet, roughly the size of Uranus. Modeling shows that even if the event happened 4.5 billion years ago, when the planets were still forming, ...
