Hati and Skǫll
According to mythology, Hati and Skǫll are the wolves that follow the moon, Màni, and Sòl, or the sun, without ever stopping.
The name Hati has an etymology; it can in fact be related to Old Norse hatr "hatred" (always note how Scandinavian influenced English).
It could therefore be traced back to the adjective "hateful" even if some connect it to the adjective "ready to dodge".
Skǫll, in whatever form it is found, does not have a precise etymology, however it is thought to derive from the verb skolla "to fall". The verb could also be associated with "stealth".
In fact, it should be noted that Skolli is the nickname given to the fox, that is "(she who) moves stealthily".
Very little is known about these wolves, but one thing is sure, even if they never seem to reach the celestial bodies, one day one of them will eat the sun darkening the earth and the other will tear the moon by filling the sky with blood, those will be of the signs of Ragnarök.
It is not entirely clear which of them is chasing the sun and who is chasing the moon.
Medieval Icelandic historian Snorri Sturluson states that Skoll chases the sun and Hati the moon. However, Snorri's source in this passage, the Eddic poem Grímnismál, says the following in the relevant verse:
"Sköll heitir ulfr, er fylgir inu skírleita goði til varna viðar, en annarr Hati, hann er Hróðvitnis sonr, sá skal fyr heiða brúði himins."
Skǫll is the name of the wolf Who follows the shining priest into the desolate forest, and the other is Hati, Son of Hróðvitnir, Who pursues the luminous bride of heaven. The noun used for Skoll's prey, goði ("priest"), is masculine, and the noun used for Hati's prey, brúðr ("bride") is feminine.
Since Máni (the moon) is male and Sól (the sun) is female, the wording of this verse strongly suggests that Skǫll chases the moon and Hati the sun.
These wolves were also used to explain eclipses; the Vikings thought, in fact, that this happened when the wolf came one step away from eating the satellite.