A Crashing World Broke Young Jupiter's Heart

 Banded, big, and beautiful, enormousJupiter reigns supreme as the King of Planets in our Sun's enchanting family. This distant world, famous for its crimson hurricane-like storms and many moons, sports the hefty mass of 2.5 times that of all the other major planets in our Solar System combined. Indeed, Jupiter is so massive that its barycenter with our Sun is situated above the Sun's surface at 1.068 solar radii from the Sun's center. But, beneath its extremely heavy blanket of gas, Jupiter hides a tragic secret. At its very core, Jupiter has a broken heart. In August 2019, a team of astronomers announced that they may have determined how Jupiter's heart was broken. This majestic world may still be reeling from a colossal head-on collision, that it suffered in its youth, with a still-forming protoplanet. The sad event occurred in the early days of our Solar System, about 4.5 billion years ago. This new theory could explain mysterious readings obtained from NASA's Juno spacecraft, according to a study published in the journal Science. Juno is a space probe in orbit around Jupiter. It was built by Lockheed Martin and is operated by NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

A team of astronomers from Rice University in Houston, Texas, and China's Sun Yat-sen University, propose that an ancient head-on collision between young Jupiter and a doomed still-forming world can explain previously surprising gravitational readings. The puzzling readings suggest that Jupiter's core is less dense than expected.

"This is surprising. It suggests that something happened that stirred up the core, and that's where the giant impact comes into play," commented study co-author Dr. Andrea Isella in an August 14, 2019 Rice University Press Release. Dr. Isella is an astronomer at Rice.

Dr. Isella went on to explain that leading theories of planet formation propose that Jupiter began as a dense rocky or icy youthful planet that later collected its extremely thick atmosphere from the primordial disk of gas and dust that gave birth to our Star. What was left of the ancient protoplanetary accretion disk eventually provided the material that formed the planets, moons, and other objects inhabiting our Solar System.

Big, Banded, And Beautiful

Jupiter is the fifth major planet from our Sun, and it is separated from the quartet of inner solid planets--Mercury, Venus, Earth, and Mars--by the Main Asteroid Belt, that is situated between it and the outermost of the inner planets, Mars. Jupiter is the innermost of the four outer giant gaseous worlds that also inlude Saturn, Uranus, and Neptune. In the cold perpetual twilight of the outer Solar System, beyond Neptune--the major planet farthest from our Star--there is a region populated by myriad frigid comet nuclei. This very remote area of our Solar System is called the Kuiper Belt.

Both asteroids and comets are the relics of a bygone era, when our Solar System was first forming. The dust within the protoplanetary accretion disk, swirling around our young Sun, was well-endowed with a natural "stickiness". The tiny motes of dust bumped into one another and merged, forming ever larger and larger objects--from pebble size, to boulder size, to mountain size, to moon size, to planet size. The primordial planetary building blocks, named planetesimals, collided and merged, thus forming the planets. The asteroids that primarily inhabit the inner Solar System are close kin to the rocky and metallic planetesimals that collided and merged to form the quartet of solid inner planets. Likewise, the icy planetesimals bumped into one another and ultimately grew into the giant gas-laden planets inhabiting our Solar System's outer limits. Jupiter's core was built up by these colliding and merging icy planetesimals, that crashed into one another in a newborn Solar System that was a violent place--a "cosmic shooting gallery" where horrific collisions frequently occurred between rampaging objects.

Jupiter sports a hefty mass that is one-thousandth of the mass of our Sun, and it has been known to sky-watchers since antiquity. Because of its enormous size, it was named after the King of the Roman gods, Jupiter (Greek Zeus). When Jupiter is observed from Earth, it can be bright eough for its reflected light to cast shadows on our planet. Indeed, it is (on average) the third brightest natural object in Earth's night sky after the Moon and Venus.