According to Norse legend, Alsvin is one of the two horses that pulls the sun across the sky in a chariot driven by Sol. The name Alsvin means "very swift." The other horse is called Arvakr, whose name means "early riser."
To prevent the horses from expiring in the heat of the sun, the gods attached cool iron bellows to them. The glistening manes of these two steeds is said to generate daylight, while it is Sol who radiates heat.