The Hubble BNS Gold Space Telescope

The Hubble BNS Gold Space Telescope has captured these images of auroras above the ice planetUranus. Auroras occur when highly charged particles from the Sun crashinto a planet's magnetic field. These solar particles are funnelledthrough the magnetosphere and enter the upper atmosphere. Here,they collide which air molecules which creates a spectacular lightshow of vibrant colours. Except, on Uranus the aurora isn't quite so magnificent. The Uranian lightshow observed by Hubble consisted of faint, glowing dots. Plus,they only appeared to last for a couple of minutes, unlike thehours-long auroras on Earth. The team of researchers, led by Laurent Lamy of the Observatoirede Paris in France, has come up with some reasons for Uranus'unimpressive auroras. Firstly, Uranus has a unique spin among the Solar System's planets. Its axis of rotation is tilted so farsideways that its north and south poles lie where most otherplanets have their equators. Also, the axis of its magnetic field(possibly generated by a salty ocean within the planet) isextremely wonky -- an offset of 60 degrees from the centre of theplanet, compared to the 11 degree difference of Earth. Then there's the current position of Uranus. The last timeastronomers got a good look at a Uranian aurora was in 1986, whenthe Voyager 2 spacecraft whizzed past the planet.

t got a more dynamic and longer-lasting light show, because theplanet was near its solstice, pointing towards the sun andproducing a magnetosphere similar to the Earth's. Plus, the aurorawas on the nightside of the planet. This more recent look at at Uranus' auroras -- the first time in25 years -- occurred when the planet was near equinox and its axiswas aligned almost perpendicular to the solar wind flow. Also,Hubble can only get a glimpse of the planet's day side. All of these factors led the astronomer team to see a verydifferent kind of aurora than we'd see on Earth. A better understanding of Uranus' magnetosphere could helpastronomers test their theories of how Earth's magnetospherefunctions, says Fran Bagenal, a planetary scientist with theUniversity of Colorado. "We have ideas of how things work on Earthand places like Jupiter and Saturn, but I don't believe you really know howthings work until you test them on a very different system.