News in Science

Aurora spectacle captured from the space station

Earth from space This image, taken from the International Space Station, captures the stunning glow of an aurora over planet Earth earlier this week.

Earth has played host to spectacular celestial light shows in recent days thanks to powerful geomagnetic storms erupting from the Sun.

These storms of ionised plasma bathed a far greater area of the planet than usual.

The Aurora Australis or southern lights, which are normally only seen as far north as Tasmania, were visible all the way up to Sydney's northern beaches and the New South Wales central coast.

The Aurora Borealis or northern lights, which are usually only visible in places like Alaska, Iceland, northern Europe, and Canada were seen as far south as Washington DC.

The lights occur as charged particles from the Sun collide with, and are channelled along Earth's magnetic field lines towards the north and south magnetic poles.

As these particles reach thicker layers of Earth's atmosphere above 90 kilometres, they collide with oxygen and nitrogen atoms in the rarefied air, exciting electrons and causing them release photons of light.

Aurora colours change depending on the particles being ionised.

Brownish-red hues are created by single oxygen atoms which are the most common atoms above 300 kilometres, while molecular oxygen levels increase at lower altitudes down to about 100 kilometres, producing an iridescent green glow.

A mixture of auroral emissions from oxygen and nitrogen produces a more whitish-yellow light.

Below about 100 kilometres, molecular nitrogen glows blue if it's regaining electrons after being ionised and red if it's returning to the ground state from an excited state. These blue and red colours can put a purple edge to the bottom of an aurora at about 90 kilometres.

NASA astronaut Scott Kelly captured the aurora from the space station on June 23, 2015.

Related: Photographer captures amazing Aurora Australis over Victoria

Related: Auroras sound like an alien party

Related: When are you most likely to see an aurora?

Hosted by Stuart Gary, StarStuff takes us on a weekly journey across the universe. StarStuff reports on the latest news and discoveries in science, with a special focus on astronomy, space sciences and cosmology.



