The first trihydrogen ions ever observed were found in the aurorae of this planet. Anomalously high 
The first trihydrogen ions ever observed were found in the aurorae of this planet. Anomalously high amounts of argon, krypton, and xenon in its atmosphere likely come from captured Kuiper Belt objects. It has the shortest period of rotation of planets in the solar system. In 1994, plumes in this planet's atmosphere were caused by the fragments of the Shoemaker-Levy 9 comet. Its four largest moons were discovered independently by Simon Marius and Galileo; the biggest of those is Ganymede. For 10 points, name this fifth planet from the Sun with a Great Red Spot.
The first trihydrogen ions ever observed were found in the aurorae of this planet.
Jupiter