martedì 9 novembre 2010

A strange flickering light



The Valkyrior are warlike virgins, mounted upon horses and armed with helmets and spears. [...] When they ride forth on their errand, their armour sheds a strange flickering light, which flashes up over the northern skies, making what men call the "aurora borealis", or "Northern Lights".

("Bulfinch's Mythology", by Thomas Bulfinch, 1855)

Polar Auroras, also known as northern and southern (polar) lights, are natural light displays in the sky, particularly in the polar regions, and usually observed at night.
Typically the aurora appears either as a diffuse glow or as "curtains" that approximately extend in the east-west direction. At some times, they form "quiet arcs"; at others ("active aurora"), they evolve and change constantly.

Nessun commento:

Posta un commento