Is it true that Ganymede has a magnetic field like a planet?
Inside GanymedeOne of Galileo’s major discoveries was made during its very first orbital encounter – with Ganymede, Jupiter’s largest moon. About half an hour before the spacecraft reached its closest approach, the radio-noise instrument, designed to record ambient electrical fields, began to go haywire. The relatively quiet background radio signals seen throughout most of the Jovian system changed abruptly to a complex, active radio spectrum. For 45 minutes the activity remained intense, and then it ceased as suddenly as it had begun. When the radio noise commenced, the magnetometer readings shot up fivefold. Plasma researchers had seen signatures of this sort before, when spacecraft carrying similar instruments entered and exited magnetospheres at Earth, Jupiter, Saturn, Uranus and Neptune. Two subsequent Ganymede flybys confirmed their suspicions: the moon is magnetized, generating a dipole field similar to those of these planets. No other satellite has such a field.
One of Galileo’s major discoveries was made during its very first orbital encounter – with Ganymede, Jupiter’s largest moon. About half an hour before the spacecraft reached its closest approach, the radio-noise instrument, designed to record ambient electrical fields, began to go haywire. The relatively quiet background radio signals seen throughout most of the Jovian system changed abruptly to a complex, active radio spectrum. For 45 minutes the activity remained intense, and then it ceased as suddenly as it had begun. When the radio noise commenced, the magnetometer readings shot up fivefold. Plasma researchers had seen signatures of this sort before, when spacecraft carrying similar instruments entered and exited magnetospheres at Earth, Jupiter, Saturn, Uranus and Neptune. Two subsequent Ganymede flybys confirmed their suspicions: the moon is magnetized, generating a dipole field similar to those of these planets. No other satellite has such a field. Earth’s moon and Mars may have
