Jupiter's Auroras Discovered By NASA Juno Spacecraft

NASA has spacecraft orbiting planets and gathering data to help scientists learn more about our solar system. One of the spacecraft is currently operating is called Juno, and it's in orbit around Jupiter. Juno has detected new auroral emissions on Jupiter that appear to ripple over the poles of the planet.

The aurora was discovered using the Ultraviolet Spectrograph (UVS) aboard Juno. NASA says the aurora are characterized by very faint ring-shaped emissions expanding rapidly over time at speeds between two and 4.8 miles per second. Scientists believe the aurora are triggered by charged particles coming from the edge of the giant planet's magnetosphere.

Scientists believe the faint ultraviolet features originate millions of miles from Jupiter near the Jovian magnetosphere's boundary with the solar wind. The solar wind is a supersonic stream of charged particles emitted from the sun, and when the particles reach Jupiter, they interact with its magnetosphere. Scientists currently don't understand the interaction between the solar wind and Jupiter's magnetosphere very well.

Auroras on Jupiter link to charged particles within the magnetosphere, just as they are on Earth. One significant difference is that Jupiter has a massively more powerful magnetosphere to the tune of about 20,000 times stronger than the Earth's. The incredible strength of Jupiter's magnetosphere allows it to deflect solar wind from up to 4 million miles away from the planet.

Scientists say the high-latitude location of the auroral rings indicates the particles causing the emissions are coming from the magnetosphere of the planet. Charged particles recorded by the UVS instrument appear to be coming from the outer reaches of the magnetosphere, where plasma from solar wind interacts with Jovian plasma. Researchers believe the interaction could create ring-like features known as Kelvin-Helmholtz instabilities able to travel along the magnetic field lines of Jupiter. Another possibility for causing the auroral features could be magnetic reconnection events on the dayside of the planet.