

Magnetospheres of the Outer Planets

Jupiter's magnetic field

The strong magnetic field of Jupiter influences a vast region of space, extending well beyond the Galilean moons. The volcanic moon Io spews out gases (mostly sulfur dioxide) that become ionized and trapped in Jupiter’s magnetic field. Some of these charged particles become accelerated to high energies and fill the giant magnetosphere with hot plasma. Electrons carrying strong electrical currents that couple the magnetosphere to the spinning planet bombard the atmosphere and excite intense aurora near Jupiter’s poles. (Courtesy John Spencer, SwRI)

A magnetosphere is the sphere of influence of a planet’s magnetic field. The giant planets of the outer solar system have strong magnetic fields whose influence extends far beyond their planets, encompassing many of their moons.

The stronger the magnetic field, the larger the magnetosphere. The Earth’s magnetosphere is about ten times the size of the planet – but the whole of the terrestrial magnetosphere would fit inside the planet Jupiter. Over a thousand suns would fit inside the vast volume of Jupiter’s magnetosphere.

The volcanic moons Io and Enceladus eject up to a ton of gases every second into the surrounding space. The interaction of magnetospheric material with the gases from these moons produces a range of phenomena from strong electrical currents to radio emissions to bright auroras.

Magnetospheres can be studied in several ways: We apply the physics of plasmas to model magnetospheric processes and compare model calculations with measurements made by particle detectors flying through a magnetosphere, and with different forms of emissions detected by telescopes and spectrographs based at Earth or on spacecraft.

LASP scientists are:

  • Studying how the solar wind interacts with the giant magnetosphere of Jupiter
  • Investigating what ground-based telescope observations of infrared emissions of H3+ ions can tell us about Jupiter’s aurora
  • Modeling how magnetospheric plasma interacts with the volcanic moon Io spreading tons of neutral and ionized components across the Jovian system
  • Simulating Cassini spacecraft observations of water products spewed out in volcanic plumes from Saturn’s moon Enceladus
  • Analyzing particle data obtained by the New Horizons spacecraft as it flew past Jupiter on its way to Pluto
  • Preparing for the upcoming Juno mission to Jupiter (launch: 2011); and the flyby of Pluto by New Horizons (2015)