Magnetosphere of Jupiter

Magnetosphere of Jupiter
False-color image of aurorae on the north pole of Jupiter, as viewed by the Hubble Space Telescope
Discovery[1]
Discovered byPioneer 10
Discovery dateDecember 1973
Internal field[2][3][4]
Radius of Jupiter71,492 km
Magnetic moment2.83 × 1020 T·m3
Equatorial field strength417.0 μT (4.170 G)
Dipole tilt~10°
Magnetic pole longitude~159°
Rotation period9h 55m 29.7 ± 0.1s
Solar wind parameters[5]
Speed400 km/s
IMF strength1 nT
Density0.4 cm−3
Magnetospheric parameters[6][7][8]
TypeIntrinsic
Bow shock distance~82 RJ
Magnetopause distance50–100 RJ
Magnetotail lengthup to 7000 RJ
Main ionsOn+, Sn+ and H+
Plasma sourcesIo, solar wind, ionosphere
Mass loading rate~1000 kg/s
Maximum plasma density2000 cm−3
Maximum particle energyup to 100 MeV
Aurora[9]
Spectrumradio, near-IR, UV and X-ray
Total power100 TW
Radio emission frequencies0.01–40 MHz

The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.

Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is theorized to be composed of liquid metallic hydrogen. Volcanic eruptions on Jupiter's moon Io eject large amounts of sulfur dioxide gas into space, forming a large torus around the planet. Jupiter's magnetic field forces the torus to rotate with the same angular velocity and direction as the planet. The torus in turn loads the magnetic field with plasma, in the process stretching it into a pancake-like structure called a magnetodisk. In effect, Jupiter's magnetosphere is internally driven, shaped primarily by Io's plasma and its own rotation, rather than by the solar wind as at Earth's magnetosphere.[6] Strong currents in the magnetosphere generate permanent aurorae around the planet's poles and intense variable radio emissions, which means that Jupiter can be thought of as a very weak radio pulsar. Jupiter's aurorae have been observed in almost all parts of the electromagnetic spectrum, including infrared, visible, ultraviolet and soft X-rays.

The action of the magnetosphere traps and accelerates particles, producing intense belts of radiation similar to Earth's Van Allen belts, but thousands of times stronger.[citation needed] The interaction of energetic particles with the surfaces of Jupiter's largest moons markedly affects their chemical and physical properties. Those same particles also affect and are affected by the motions of the particles within Jupiter's tenuous planetary ring system. Radiation belts present a significant hazard for spacecraft and potentially to human space travellers.

  1. ^ Cite error: The named reference Smith was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Khurana3 was invoked but never defined (see the help page).
  3. ^ Russel, 1993, p. 694
  4. ^ Cite error: The named reference Zarka375 was invoked but never defined (see the help page).
  5. ^ Blanc, 2005, p. 238 (Table III)
  6. ^ a b Cite error: The named reference Khurana1 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Khurana5 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Bolton was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Bhardwaj342 was invoked but never defined (see the help page).