Two beasts of Norse mythology are set to trouble the skies of northern Europe on Tuesday for the world's first solar eclipse of 2011.
Ancient Viking legends recount that a giant wolf named Skoll chases the Moon, and its brother Hati pursues the Sun -- and if either sinks their teeth into one and holds it back, an eclipse occurs.
For astronomers, though, eclipses are less superstitious affairs, occurring when the Moon swings between the Sun and Earth.
Tuesday's event will be a partial eclipse.
This occurs when a fraction of the Moon obscures the Sun, and to those in its shadow a "bite" seems to have been taken out of the solar face.
The tale of Skoll and Hati, the descendants of giantesses, is enshrined in 13th-century Icelandic literature, which recounts:
Follows the glittering god,
And the son of Hrothvitnir, Hati, awaits
The burning bride of heaven."
If either wolf caught up with Sun or the Moon, humans must scare the beast off with as much noise as possible in order to restore light, according to Norse beliefs.
Even so, at the twilight of the gods -- a doomsday event known as Ragnarok -- any human intervention would be useless. The two wolves would finally get to devour their booty.