An energetic head-on collision between a large planetary embryo and the proto-Jupiter about 4.5 billion years ago could explain puzzling gravitational readings from NASA’s Juno spacecraft, which suggest that Jupiter’s core is less dense and more extended that expected. An artist’s impression of a collision between the proto-Jupiter and a massive protoplanet in the early Solar System. Image credit: K. Suda & Y. Akimoto, Mabuchi Design Office...