Auroras on Earth are stunning to watch, but have you ever wondered what they might look like on other planets?
We took a journey to some alien worlds to find out what auroras look like there. There is no doubt that extraterrestrial auroras can be very beautiful on other places in the Universe, and sometimes this light show can be very unique.
On Earth, an aurora is created
when atoms in solar plasma interacts with atoms in Earth's upper atmosphere.
In our solar system, there are many bodies that generate a substantial magnetic field.
So you could see an aurora on Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune, but it would not be
possible on Venus, the Earth's moon, comets, and asteroids.
In 2010, the Cassini spacecraft observed Saturn's radio aurora. It turned out that there were some
similarities and some contrasts between the radio auroral emissions generated at Saturn and those at Earth.
Earth also has radio auroral emissions and results showed that the process that generates radio
aurora appears to be the same at both planets.
Interestingly, there are two minor differences between the aurora at Earth and Saturn.
At Earth, there is a cavity in the plasma above the auroral oval that rises for several thousand kilometres.
Observations showed that this is not seen at Saturn.
Secondly, radio sources were crossed at much further distances from the planet.
Cassini detected not only unusually strong electric currents, but it also provided scientists with evidence of an active aurora.
"We think that the unusual conditions responsible for these intense electric currents might have been triggered by a solar wind compression squeezing Saturn's
magnetic field and producing the observed auroras," said Emma Bunce, a team member from the University of Leicester in the UK.
Image of Saturn's aurora seen at ultraviolet wavelengths. The spiral shape seen here is similar to the distorted radio aurora visualised
by the team and also indicates enhanced auroral activity. (Credit: ESA/NASA/Hubble)
This wonderful image was taken by Hubble Space Telescope and shows a close-up view of an electric-blue aurora that is
eerily glowing one half billion miles away on the giant planet Jupiter.
Credit: Hubble Space Telescope
Though the aurora resembles the same phenomenon that crowns Earth's polar regions, the Hubble image shows unique emissions from the
magnetic "footprints" of three of Jupiter's largest moons.
Auroral footprints can be seen in this image from Io (along the lefthand limb), Ganymede (near the center), and Europa
(just below and to the right of Ganymede's auroral footprint). These emissions, produced by electric currents generated by the satellites, flow along Jupiter's magnetic field, bouncing in and out of the upper atmosphere. They are unlike anything seen on Earth.
To see an aurora on Jupiter is not a unique event. Jupiter has a permanent ring of auroral light surrounding each of its poles.
it has long been believed that the light originates from Io, but new research suggest the Sun also plays a vital role in creating the lights.
Io can control Jupiter's auroras over long timescales, but "this does not rule out contributions from the solar wind,"
says Margaret Kivelson of the University of California, Los Angeles.
Although a lot is known about the blue light, there are still some mysteries to be solved. Scientists must attempt to
find out how the charged particles are accelerated along Jupiter's magnetic field lines. This can hopefully be accomplished
when Juno spacecraft reaches Jupiter in 2016.
Aurora On Uranus - Credit: Nicmos
The most remarkable magnetosphere in the solar system was found by Voyager 2 in its encounter with Uranus.
This aurora was found at the feet of magnetic field lines threading only the tail side of the middle magnetosphere,
as though it were excited by connection to a partial ring current, and was apparently co-located with the sources of
whistler-mode plasma waves and some types of kilometric radio waves (UKR) also observed by Voyager at Uranus.
To see an aurora on Mars is a unique experience, but some years ago, using the ultraviolet spectrometer
(SPICAM) on board the Mars Express satellite, Jean-Loup Bertaux of the Service d'Aeronomie du CNRS in France and
his colleagues observed a Martian aurora.
Unlike the other large planets' celestial shows, which occur near the poles, the light show above the Red Planet
manifests around areas of magnetized rock in the planet's crust.
"Mars has no internally generated, planetary-scale magnetic field," explains Bill Sandel of the University of Arizona.
"It has what are called 'crustal magnetic anomalies' scattered around the Martian surface, remnants of what presumably was Mars's
planetary-scale magnetic field that was active when the planet was younger."
The aurora measured some 30 kilometers across and appeared about 130 kilometers above the surface. It corresponds to a
distinct type of aurora not seen before in the solar system.
An artist's impression of auroras on Mars's night side
-Image courtesy M. Holmström (IRF)/ESA
For the time being nothing can be said about Pluto. Whether it is possible or not to see an aurora on Pluto remains still a mystery.
And finally, perhaps this is what it looks like when E.T. is watching an aurora on an alien planet somewhere in the Universe.
Explaining How An Aurora Is Created
Most of us enjoy to watch the beautiful lights in the night sky known as aurora.
These wonderful light display appears primarily over the polar regions. But what exactly causes the aurora?
Radio Emission From Ultracool Dwarf Detected By Arecibo Telescope
The Arecibo Telescope in Puerto Rico has discovered sporadic bursts of polarized radio emission from the T6.5 brown J1047+21.
Because Arecibo is a single, fixed-dish telescope, it has a restricted practical sensitivity to weak, quiescent emission from radio sources...
Invader From Another Galaxy
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
Located about 2000 light-years from Earth in the southern constellation of Fornax (the Furnace), the Jupiter-like planet orbits a dying star of
extragalactic origin and risks to be engulfed by it.
Power To See Most Distant Objects In The Universe
The 3C294, is one of the most distant galaxies recorded by Chandra, the most sophisticated X-ray observatory ever built.
The cluster 3C294 is even 40 percent farther (!) than the next most distant x-ray galaxy cluster.
Chandra focus on X-rays from high-energy regions of the Universe and see the invisible.
It is so sensitive that it can capture images of particles as they disappear into a black hole deep in outer space.
"Pillars Of Creation" Are Gone
Every time you look at the beautiful and famous image of the Pillars of Creation taken by Hubble back in 1995,
you are actually admiring something that no longer exists.
In fact, the Pillars of Creation were already long gone by the time the image was captured!