Which wolf chases the sun across the sky?

The wolf that chases the Sun across the sky is Sköll.

In Norse mythology, Sköll pursues Sól, the personified Sun, as she drives her chariot across the heavens. The chase explains the Sun’s relentless movement through the sky: she must keep ahead of the wolf. At Ragnarök, Sköll is foretold to catch and devour her, plunging the world into darkness before the final destruction and renewal.

Sköll is often confused with Hati, another wolf associated with the celestial bodies. Hati pursues Máni, the personified Moon, while Sköll follows the Sun. Both wolves are commonly described as offspring of Fenrir and an unnamed giantess, although details vary among sources. The names also appear in different spellings, including Skoll and Hróðvitnisson in connection with Hati.

The story comes chiefly from Snorri Sturluson’s Prose Edda. Some scholars have linked the wolf imagery to atmospheric phenomena such as sun dogs and moon dogs, but that interpretation is modern rather than the central mythological explanation.