Merrillville Community Planetarium
Bringing the Universe to the Merrillville Schools and Northwest Indiana

Jupiter's Great Blue Spot

Jupiter’s Great Blue Spot (GBS) isn’t visible with through a telescope, like the Great Red Spot. GBS is the location of an unusual magnetic spot near Jupiter’s equator. It appears blue in polarity images from the Juno spacecraft.

Jupiter’s magnetic field is quite strange compared to other planets with magnetic fields. Earth has two magnetic poles, one in each hemisphere located at the spin axis, at our North and South Poles. Jupiter has a normal southern magnetic field, located at its spin axis at its South Pole. The northern magnetic pole is more like a field, with a swirled shape and more undefined. There is a third magnetic field that has the southern pole charge, located at its equator. It appears as a Great Blue Spot in magnetic images.

Jupiter could be experiencing a magnetic polar reversal, where the positive charge flips places with the negative charge. It has happened on Earth many, many times. It is recorded in the rocks formed on the Atlantic Ocean floor, spreading outward in two directions from the Mid-Atlantic Ridge. Earth’s magnetic field is a result of the spinning liquid metallic core. Jupiter’s liquid metallic hydrogen layer creates its magnetic field. The third magnetic field may just be a result of the hydrogen mixing with dissolved rock and ice, causing strange electrical currents. Jupiter’s magnetic field is 20,000 times more powerful than Earth’s magnetic field and is the strongest magnetic field in our solar system.