I watched what I thought were fantastic shadows outlined in the sky by the spectral luminosity of the [Milky Way] as it flowed through Perseus, Cassiopeia, Cepheus, and Cygnus. Then suddenly all the stars were blotted from the sky – even bright Deneb and Vega ahead, and the lone Altair and Fomalhaut behind us.

– “The Very Old Folk“

Lovecraft was a dedicated amateur astronomer in his youth and held a life-long interest in the topic; see here for more details. Unsurprisingly various celestial objects appear in his (and other Mythos author’s) stories. For a comprehensive overview, wikipedia offers such; for our purposes, we will hit the highlights, covering the real stars only and leaving the fantastical ones and assorted renamed planets in our solar system (Cykranosh and the lot) aside.

Aldebaran – This orange giant (its name coming from the Arabic ‘al-dabarān’ meaning “the Follower” because of its seeming to trail after the nearby Pleiadies) is part of the constellation Taurus and appears to be part of the Hyades (though it is 150 light years distant). Hastur is said to be imprisoned here or on a planet circling the star.

Algol – From the Arabic ‘ra’s al-ghūl’ (the Head of the Ghoul) has been dubbed “The Demon Star” in English. In Beyond the Wall of Sleep, Lovecraft places the cataclysmic battle between the possessing being of light in the story and its nemesis here.

Celaeno – One of the Pleiadies, Celaeno’s 4th planet is home to what has been dubbed The Great Library of Celaeno, where the secrets that the Great Old Ones stole from the Elder Gods is stored.

Ah NASA, what great pictures you provide.

Fomalhaut – From the Arabic ‘fum al-ḥawt’ (“The Mouth of the Fish”), Fomalhaut is part of the constellation Piscis Austrinus. As one of the few bright stars in that region of the sky, Fomalhaut is often described in rather poetic language – “The loneliness of this star, added to the somber signs of approaching autumn, sometimes gives one a touch of melancholy. In November and December, when the winter stillness has fallen upon us, a glance toward the southwest will discover Fomalhaut, still placid and alone.” In the Cthulhu Mythos, the star is the home of Cthugghua (technically it lives in orbit of the small star Korvaz).

the Hyades – Somewhere within this star cluster is a world orbiting a binary star; this is Carcosa.

Polaris – Lovecraft wrote a story by that name, in which the pole-star takes on a sort of malign presence, connecting the narrator in the present with the long-fallen city of Olathoë, and going so far as to induce him into slumber by means of a poem, so that the city would be overrun by the terrible (and weirdly racist) Inutos.  No doubt one rarely has a story in which a star is an actual villain; in the story Polaris is described as “winking hideously like an insane watching eye which strives to convey some strange message, yet recalls nothing save that it once had a message to convey”.

Finally, Walter Gillman feels a strange pull from the sky from a “spot in the sky between Hydra and Argo” that is likely the location of a world orbiting three suns in which dwell the Elder Things and serves as a vaction spot for Keziah Mason and friends.