Viewing Saturn’s northern polar region for a period of seven months, the NASA/ESA Hubble Space telescope snapped a series of stunning images of auroras dancing in the sky. The observations were taken before and after the Saturnian northern summer solstice.
On Earth, auroras are mainly created by particles originally emitted by the Sun in the form of solar wind.
When this stream of electrically charged particles gets close to our planet, it interacts with the magnetic field, which acts as a gigantic shield.
While it protects Earth’s environment from solar wind particles, it can also trap a small fraction of them.
Particles trapped within the magnetosphere can be energized and then follow the magnetic field lines down to the magnetic poles. There, they interact with oxygen and nitrogen atoms in the upper layers of the atmosphere, creating the flickering, colorful lights visible in the polar regions here on Earth.
However, these auroras are not unique to our home planet. Other planets in our Solar System have been found to have similar auroras. Among them are the four gas giants: Jupiter, Saturn, Uranus and Neptune.
Because the atmosphere of the gaseous planets is dominated by hydrogen, these auroras can only be seen in ultraviolet wavelengths.
Hubble allowed astronomers to monitor the behavior of the auroras at Saturn’s north pole over an extended period of time.
The observations were coordinated with the ‘Grand Finale’ of NASA’s Cassini orbiter, when the spacecraft simultaneously probed the auroral regions of Saturn.
The Hubble data allowed scientists to learn more about Saturn’s magnetosphere. The images show a rich variety of emissions with highly variable localized features.
The variability of the Saturnian auroras is influenced by both the solar wind and the rapid rotation of the giant planet, which lasts only about 11 hours.
On top of this, the northern aurora displays two distinct peaks in brightness — at dawn and just before midnight.
The latter peak, unreported before, seems specific to the interaction of the solar wind with the magnetosphere at Saturn’s solstice.