Astronomers have detected a bright spot with a trailing tail in Jupiter鈥檚 aurora, caused by an electromagnetic connection to the planet鈥檚 moon, Europa.
For more than a decade, the Hubble Space Telescope has returned images of the aurora at Jupiter鈥檚 poles as the emissions light up in ultraviolet wavelengths. You can watch movies of the aurora .
Scientists have long known that Io, the innermost Galilean moon, triggers a bright auroral spot, or 鈥渇ootprint鈥�, in the light show. That footprint boasts a tail that streaks halfway around the planet.
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Now Denis Grodent at the University of Li猫ge, Belgium, and his team say Europa interacts in a similar way, although on a fainter scale. And for the first time, they have detected a dim, short auroral tail associated with Europa鈥檚 footprint.
Volcanic action
Jupiter鈥檚 auroras are produced by charged particles zipping down the planet鈥檚 magnetic field lines to the upper atmosphere where they excite gases, causing them to glow. On Earth, the same process produces the Northern and Southern lights.
But scientists are still unlocking the secrets of the enigmatic lights on Jupiter, which seem to have a wide range of influences.
Several of Jupiter鈥檚 moons are thought to play a role. In the case of Io, scientists believe the moon鈥檚 ongoing volcanism produces gases which become charged and carry strong electrical currents along the arcing magnetic lines into Jupiter鈥檚 atmosphere.
Something in the air?
鈥淎 very similar process apparently occurs at Europa,鈥� Grodent鈥檚 team writes, having studied 45 Hubble images of the aurora showing the moon鈥檚 footprint and tail.
But Europa is not thought to be volcanic, so what could produce the electrical current that zips along and eventually gives rise to Europa鈥檚 auroral footprint?
鈥淲e鈥檙e looking for something either within the moon鈥檚 surface or in its atmosphere that鈥檚 electrically conducting,鈥� says John Clarke, a space physicist at Boston University, US. While the surface is a possibility, Clarke told 麻豆传媒, the ionosphere should be the first place to look.
Journal reference: Geophysical Research Letters (DOI: 10.1029/2005GL025487)
