30 January 2010
Amazing Pic! Northern Lights from Space Station
Fantastic NASA photographs taken by astronauts travelling on the International Space Station and during missions on board space shuttles have shown that nature's light show is clearly visible miles outside the Earth's atmosphere.
The shimmering waves and swirls, caused by charged particles colliding in the earth's atmosphere, are usually observed from the polar regions, yet rarely seen from above.
The aurora borealis - or Northern Lights - most often occurs from September to October and from March to April and is visible in the northern hemisphere.
Its southern counterpart, the aurora australis – Latin for South – is visible from Antarctica, South America and Australasia.
Both are caused by an interaction between the Earth's magnetic field and solar wind. Charged particles from the magnetosphere, mostly electrons, collide with atoms and molecules from the upper atmosphere at altitudes of 50 miles, causing the eerie light.
Collisions in the atmosphere cause the electrons to take quantum leaps, converting their energy into a visible light.
The luminous waves are usually red or green, created from atomic oxygen, but nitrogen can cause pink or blue auroras and helium gives off a purple glow. Neon is responsible for the rare orange flares.
The auroras' ghostly glow has proved the inspiration for literature and film, including Philip Pullman's novel, 'Northern Lights'.