Dropplet collisions at 5000fps

Northern Lights: Chasing the aurora borealis

An electron interacts with neutral atoms and causes light of various colours to be emitted. What happens when the aurora brightens is particles that start at the sun - and most of these are electrons - are brought by solar winds towards the Earth and guided by the Earth's magnetic poles. When the particles interact with the Earth's atmosphere, they excite molecules already there, and they emit light. The colour of that light is dependent upon which gases in the Earth's atmosphere - oxygen, nitrogen, or some other - are being excited. And when the solar winds are stronger and more 'gusty', the auroras will be more brilliant.

Aerial viewing of Greece

How genuine are the tears in North Korea?

By Tom Geoghegan BBC News Magazine

The outpouring of grief in North Korea after the passing of Kim Jong-il has been fervent and widespread. So are the people sincerely feeling this loss or are they behaving as they think they should?

It's not easy to produce tears when you're not really feeling it but you could fake weeping and wailing and this mass hysteria makes it impossible to tell what is real. There's a kind of arms race situation in which you have to express yourself more and more extremely in order to demonstrate that you are feeling the orthodox emotions. A lot of it is perfectly compatible with acting. That isn't to say that it is acting, however.

Anthony Daniels, psychiatrist

La chanteuse Cesaria Evora est morte

La chanteuse Cesaria Evora, connue sous le nom de la "diva aux pieds nus", est morte, samedi 17 décembre, à l'âge de 70 ans.

                         Sodade, 1992

La chanson Sodade raconte l’histoire de ces Capverdiens obligés de s’exiler encouragés par le gouvernement portugais, à cause des famines et sécheresses qui ont frappé le pays à  plusieurs reprises

% of population who have never used the internet

Les consequences d'une sortie de l'euro

Le retour au franc provoquerait un séisme économique et social