Last year might have belonged to Pluto, but by all accounts this is going to be the year of Jupiter. That's because the Juno spacecraft is completing its nearly five-year journey to reach the giant planet on July 4, where it will enter orbit to study the Jovian atmosphere. In preparation, astronomers have been training their telescopes on Jupiter to assist Juno in its mission – and the Hubble just caught a beautiful light show at the planet's north pole.
Using the Hubble Space Telescope's ultraviolet sensing equipment, researchers were able to capture a Jovian aurora bigger than the size of the Earth. The image, seen here, was released by the European Space Agency (ESA) today and is actually a composite of two shots. The first is an optical shot taken by Hubble in spring 2014 and the second comes from its ultraviolet sensors and was taken this year.
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"These auroras are very dramatic and among the most active I have ever seen", says Jonathan Nichols from the University of Leicester. "It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno." Nichols is the principal investigator on a study to use Hubble to map Jupiter in advance of Juno's arrival.
The timing of the aurora observations is perfectly synced with Juno's position at the moment. The spacecraft is currently flying through and observing the solar wind that helps create the dramatic light show, just as it does here on Earth. The solar wind consists of a stream of charged particles flowing from the sun throughout the solar system. When those particles interact with a planet's atmosphere and magnetic field, a shifting glow — the aurora — is created as gas molecules release photons of light.
"While Hubble is observing and measuring the auroras on Jupiter, Juno is measuring the properties of the solar wind itself; a perfect collaboration between a telescope and a space probe," says the ESA.
In addition to the influence of the solar wind, Jupiter's aurorae are also aided by particles shed by neighboring moon Io. This makes the aurorae not only bigger than those on Earth, but also "hundreds of times more energetic," according to the ESA.
This isn't the first time Hubble has turned its attention to Jupiter's aurorae while space probes approached the planet. It worked in conjunction with the Cassini spacecraft in 2000 to do the same and with New Horizon's flyby in 2007. Still, if you're a space fan, getting to gaze upon these spectacular light shows never gets old -- as you can do now, thanks to this NASA video.