Scientists penetrate deeper into the mysteries of the Aurora ganymeda

Far from us in the Solar system, where the Earth appears to be a "pale blue dot", NASA's Galileo spacecraft (Galileo) has been in orbit around Jupiter for eight years. During this time extremely resistant to the vagaries of space weather machine – not much larger than an adult giraffe is transferred to Earth large amounts of scientific data, including observations of the magnetic field around Jupiter's moon Ganymede, which differs from the self-magnetic field of Jupiter. This mission was completed in 2003, but in a new study, scientists re-analyzed the data collected during the first flights of the Galileo probe past Ganymede, and made new conclusions about the magnetic field of the satellite Jupiter, which is unique among the magnetic fields of Solar system objects.

The structure of Ganymede's own magnetic field is formed with the participation of Jupiter's powerful magnetic field. Usually magnetospheres of planets have a smaller thickness on the side of the Sun, because they have to resist the flow of charged particles called the solar wind, however, in the case of Ganymede the function of "shield", covering the solar wind, plays the magnetosphere of Jupiter. Ganymede's own magnetosphere thus reaches only the slow streams of plasma moving round a huge planet. These slow plasma flows are directed to the poles of Ganymede and, reaching the surface, knock out the secondary particles, the study of which can give new information about the composition of the thin atmosphere of the satellite Jupiter.

In the new work group, headed by Glina by Collinson (Glyn Collinson) from the center of Goddard, NASA, USA, analyzed data from the magnetic field of Ganymede, collected with the help of Galileo in the period from 1996 to 2000, By fortunate coincidence one of the spans of the device Galileoпроходил directly over the area of the Aurora of Jupiter's moon – a place where the slow plasma streams reach the surface of Ganymede. Comparing the measurements made using the Galileo system with the observations made with the NASA Hubble space telescope (Hubble), the Collinson team was able to determine the boundaries of the zone of polar lights on the surface of Ganymede, which will help to further understand the mechanisms in accordance with which the formation of these atmospheric phenomena.

The work is published in the journal Geophysical Research Letters.