Astro2110 – The Solar System

We all are familiar with the Galilean Moons; those 4 largest moons orbiting Jupiter which Galileo discovered with his telescope, and which were subsequently named after his lovers. Three of these moons (Io, Europa, Ganymede) have created auroral bursts in Jupiter’s atmosphere, but Callisto had only yielded two potential footprints … until last month!

We know how auroral displays take place here on Earth: when our magnetic field “funnels” charged particles that are flowing to our polar regions, from the sun.  Jupiter is the site of both permanent and temporary auroras, and the temporary ones form as each of Jupiter’s moons interacts with the planet’s.

Scientists studied images captured by Hubble in 2007, searching for instances when Jupiter’s main auroras were dimmer or further from the polar regions. They found only one image where Callisto was not eclipsed by Jupiter and its auroral footprint was visible.

Jupiter is MUCH bigger than Earth, but it spins on its axis every ten hours, and as its large moons orbit Jupiter, its magnetic field continues sweeping past them. Dolon Bhattacharyya, a research scientist at Boston University, describes these moons acting “as conductors in a rapidly changing magnetic field environment,” like a battery with positive and negative potential at its ends.

Magnetic field lines connect all four Galilean moons to Jupiter, and interactions from the sun’s plasma particles and Jupiter’s magnetic field cause the magnetic fields of these moons to vibrate as the nearby electrons move more rapidly. These electrons move along the magnetic field lines from the moon into Jupiter’s atmosphere.  There, the charged particles are dropped off as auroral displays. The closer moons yield auroras with lower latitudes than those further moons like Callisto.

Callisto’s auroral footprints took so long to discover because its orbit is so far from Jupiter that the moon’s particles hit Jupiter near the polar region, which is where the gas giant’s primary auroral display lights up.

We all are familiar with the Galilean Moons; those 4 largest moons orbiting Jupiter which Galileo discovered with his telescope, and which were subsequently named after his lovers. Three of these moons (Io, Europa, Ganymede) have created auroral bursts in Jupiter’s atmosphere, but Callisto had only yielded two potential footprints … until last month!

We know how auroral displays take place here on Earth: when our magnetic field “funnels” charged particles that are flowing to our polar regions, from the sun.  Jupiter is the site of both permanent and temporary auroras, and the temporary ones form as each of Jupiter’s moons interacts with the planet’s.

Scientists studied images captured by Hubble in 2007, searching for instances when Jupiter’s main auroras were dimmer or further from the polar regions. They found only one image where Callisto was not eclipsed by Jupiter and its auroral footprint was visible.

Jupiter is MUCH bigger than Earth, but it spins on its axis every ten hours, and as its large moons orbit Jupiter, its magnetic field continues sweeping past them. Dolon Bhattacharyya, a research scientist at Boston University, describes these moons acting “as conductors in a rapidly changing magnetic field environment,” like a battery with positive and negative potential at its ends.

Magnetic field lines connect all four Galilean moons to Jupiter, and interactions from the sun’s plasma particles and Jupiter’s magnetic field cause the magnetic fields of these moons to vibrate as the nearby electrons move more rapidly. These electrons move along the magnetic field lines from the moon into Jupiter’s atmosphere.  There, the charged particles are dropped off as auroral displays. The closer moons yield auroras with lower latitudes than those further moons like Callisto.

Callisto’s auroral footprints took so long to discover because its orbit is so far from Jupiter that the moon’s particles hit Jupiter near the polar region, which is where the gas giant’s primary auroral display lights up.