Scientists from Italy, the United States and Belgium found that the two satellites of Jupiter leave traces in the planetary radiance. On Earth, the aurora is seen as the southern and northern events - dazzling manifestations of light in the night sky. Jupiter also has lights, but is caused by another process. The giant planet has a powerful magnetic field. Charged particles from the magnetosphere periodically collide with the atmosphere of the planet, causing manifestations that resemble earthly ones. But there is something that is not observed here. These are traces caused by Io or Ganymede.
All panels are displayed in a polar orthographic projection with overlapped parallels and meridians. (A) Io's footprint in the south pole of Jupiter on September 1, 2017. The main spot (top left) is followed by a series of regularly located secondary spots, alternating above and below the midline (blue). A thin blue arc with dots is a sequence of predicted Io positions with dots representing its position every 100 s. (B) As in A, but shows a later image. The main spot (blue arrow) has acquired an oval shape with an angular displacement from the average direction of the tail (middle line). (From C to E) Io's fingerprint in the northern lights on September 1, 2017. The model is not shown in C, D, and E because it is outside the visible area Researchers obtained evidence of traces when studying data sent to Earth by the NASA Juno space probe. It turned out that when Io passed close to Jupiter, this led to a double trail that appeared in the aurora borealis. It is drawn hundreds of kilometers away and disappears when the moon moves away from the planet.
Also noticed the trail from Ganymede. These are two spots in the northern lights. It is important to note that this is the only satellite of Jupiter with its own magnetic field. Then the trace can mark the contact of two magnetospheres. The study of such traces will help to understand how satellites interact with the planet and how powerful magnetic forces are in contact in their natural environment.