Data from NASA's Juno spacecraft suggests that Jupiter was shaken to its core by a colossal, head-on collision 4.5 billion years ago with a planet about 10 times more massive than Earth.According to a new study this week in the journal Nature, the planetary impact scenario can explain surprising readings about Jupiter's gravitational field that Juno has made since arriving at the solar system's largest planet in 2016. Researchers ran thousands of computer simulations for the study and found the head-on impact scenario best explained Juno's gravitational readings."We have been studying the giant planets, particularly Jupiter and Saturn, since the time of Galileo, but we still don't know exactly how they formed," said Rice University astronomer and study co-author Andrea Isella.Isella said some theories suggest Jupiter began as a dense, rocky planet that later gathered its thick atmosphere from the primordial disk of gas and dust that birthed our sun, Sol. Other theories have Jupiter forming from the gravitational collapse of a portion of the disk. In that case, Jupiter's core wouldn't have been dense and rocky from the start, but it would have become increasingly dense as gravity dragged iron and other heavy elements toward the center of the planet.