ESA Hubble Photo Release | 2018 Aug 30
Astronomers using the NASA/ESA Hubble Space telescope have taken a series of spectacular images featuring the fluttering auroras at the north pole of Saturn. The observations were taken in ultraviolet light and the resulting images provide astronomers with the most comprehensive picture so far of Saturn’s northern aurora.
In 2017, over a period of seven months, the NASA/ESA Hubble Space Telescope took images of auroras above Saturn’s north pole region using the Space Telescope Imaging Spectrograph (STIS). The observations were taken before and after the Saturnian northern summer solstice. These conditions provided the best achievable viewing of the northern auroral region for Hubble.Click to play embedded YouTube video.Credits: NASA/ESA/Hubble, L. Lamy (Observatoire de Paris),Click to play embedded YouTube video.
A. Simon (GSFC) and the OPAL Team, J. DePasquale (STScI)
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 — the region of space surrounding Earth in which charged particles are affected by its magnetic field — can be energised 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, colourful lights visible in the polar regions here on Earth [1].
However, these auroras are not unique to Earth. 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 each of the four outer planets in the Solar System is — unlike the Earth — dominated by hydrogen, Saturn’s auroras can only be seen in ultraviolet wavelengths; a part of the electromagnetic spectrum which can only be studied from space.
Hubble allowed researchers to monitor the behaviour of the auroras at Saturn's north pole over an extended period of time. The Hubble observations were coordinated with the “Grand Finale” of the Cassini spacecraft, when the spacecraft simultaneously probed the auroral regions of Saturn [2]. The Hubble data allowed astronomers to learn more about Saturn’s magnetosphere, which is the largest of any planet in the Solar System other than Jupiter. ...
Saturn's Northern Aurorae at Solstice from HST Observations
Coordinated with Cassini's Grand Finale ~ L. Lamy et al
- Geophysical Research Letters (online 17 July 2018) DOI: 10.1029/2018GL078211
arXiv.org > astro-ph > arXiv:1808.08168 > 24 Aug 2018