Astronomers using the NASA/ESA Hubble Space Telescope have captured
new images of the dancing auroral lights at Saturn’s north pole. Taken
from Hubble’s perspective in orbit around the Earth, these images
provide a detailed look at Saturn’s stormy aurorae — revealing
previously unseen dynamics in the choreography of the auroral glow.
The cause of the changing patterns in Saturn's aurorae is an ongoing
mystery in planetary science. These ultraviolet images, taken by
Hubble’s super-sensitive Advanced Camera for Surveys,
add new insight by capturing moments when Saturn’s magnetic field is
affected by bursts of particles streaming out from the Sun.
Saturn has a long, comet-like magnetic tail known as a magnetotail — as do Mercury, Jupiter, Uranus, Neptune and Earth [1]. This magnetotail is present around planets that have a magnetic field, caused by a rotating core of magnetic elements.
It appears that when bursts of particles from the Sun hit Saturn, the
planet’s magnetotail collapses and later reconfigures itself, an event
that is reflected in the dynamics of its aurorae.
Some of the bursts of light seen shooting around Saturn’s polar
regions travelled at over three times faster than the speed of the gas
giant’s rotation!
The new images also formed part of a joint observing campaign between Hubble and NASA's Cassini spacecraft,
which is currently in orbit around Saturn itself. Between them, the two
spacecraft managed to capture a 360-degree view of the planet’s aurorae
at both the north and south poles. Cassini also used optical imaging to
delve into the rainbow of colours seen in Saturn’s light shows. On
Earth, we see green curtains of light with flaming scarlet tops.
Cassini’s imaging cameras reveal similar auroral veils on Saturn, that
are red at the bottom and violet at the top.
Notes
[1] A magnetosphere is the area of space around an
astronomical object in which charged particles are controlled by that
object’s magnetic field. The magnetosphere is compressed on the side of
the sun, and on the other side it extends far beyond the object. It is
this extended region of the magnetosphere that is known as the
magnetotail.
