Is there a hidden order to the Northern Lights?

[AndrewA]

http://space.newscientist.com/article/dn13...s1_head_dn13802

The shifting, shimmering Northern Lights might be more ordered than anyone realised. New observations suggest that, contrary to expectations, some of the colourful light shows appear to be polarised, with their electromagnetic waves lined up in a common orientation.

If confirmed, the discovery will provide a powerful new tool to understand the Earth's magnetic field and the atmospheres of other planets.

Auroras shine because charged particles from the Sun, such as electrons, get captured by the Earth's magnetic field. The field channels the particles into the atmosphere above the Earth's poles, where they collide with gas particles, causing them to glow.

But scientists have long doubted the process could lead to polarised auroras. That's because there were thought to be too many atmospheric collisions for the resulting electromagnetic waves to be neatly aligned.

In fact, when Australian researcher Robert Duncan announced in 1958 that he had detected one instance of polarisation in the nocturnal display after many nights of searching, his findings were disputed and the observation was dismissed within a year.

Now, scientists working on the Norwegian island of Spitsbergen far north in the Arctic have found new evidence of the phenomenon.

Polar rain

Jean Lilensten of the National Center for Scientific Research in Grenoble, France, and colleagues used a custom-built photopolarimeter to watch the sky at various times over the last two winters. They found that at an altitude of 220 kilometres, electrons from space excite oxygen atoms to emit polarised red light.

The degree of polarisation is small

[nebula]

Andrew -

Do you understand what this "polarization" is that they are talking about?