Researchers Capture Glimpses of Uranus Auroras

Posted on April 19, 2012

Uranus Auroras

Scientists have captured images of auroras above the giant ice planet Uranus for the first time. Auroras on Uranus are fainter than they are on Earth, and the planet is more than 4 billion kilometers (2.5 billion miles) away. Detected by means of carefully scheduled observations from the Hubble Space Telescope, the newly witnessed Uranian light show consisted of short-lived, faint, glowing dots - a huge difference from the colorful curtains of light that often ring Earth's poles.

The researchers detected the luminous spots twice on the dayside of Uranus the side that is visible from Hubble. Previously, the distant aurora had only been measured using instruments on a passing spacecraft. Auroras on Uranus appear to last only a couple of minutes, unlike the auroras on Earth which can streak the sky with ghostly green and purple hues for hours.

Auroras are a feature of the magnetosphere, the area surrounding a planet that is controlled by its magnetic field and shaped by the solar wind, a steady flow of charged particles emanating from the sun. Auroras are produced in the atmosphere as charged solar wind particles accelerate in the magnetosphere and are guided by the magnetic field close to the magnetic poles.

Laurent Lamy, with the Observatoire de Paris in Meudon, France, who led the new research, says, "The magnetosphere of Uranus is very poorly known. This planet was only investigated in detail once, during the Voyager flyby, dating from 1986. Since then, we've had no opportunities to get new observations of this very unusual magnetosphere."

The results from his team, which includes researchers from France, the United Kingdom, and the United States, will be published Saturday in Geophysical Research Letters, a journal of the American Geophysical Union. The researchers suspect that the unfamiliar appearance of the newly observed auroras is due to Uranus' rotational weirdness and peculiar traits of its magnetic axis.

Photo: Laurent Lamy