Solar System

Many of the planets in our Solar System are referenced in H. P. Lovecraft's Cthulhu Mythos. Lovecraft was a passionate amateur astronomer and enjoyed inserting references to celestial bodies into his tales.
==Mercury==
Mercury is the first planet from the sun.
At some point in time, Mercury will be home to an intelligent species of "bulbous vegetable entities", whose bodies will be possessed by the Great Race of Yith after the fall of the coleopteran civilization on Earth. (: The Shadow Out of Time)
===Mercury's moon===
In the past, Mercury also had a moon, which was inhabited by a hybrid polyp species with gestalt minds. At some point, however, Mercury's moon was plunged into the sun and destroyed. (: The Transition of Titus Crow)
==Venus==
Venus is the second planet from the sun.
According to the writings of Claes van der Heyl, at some point in history creatures known as "the lords of Venus" arrived in their spaceships to "civilise" the Earth. (: "The Diary of Alonzo Typer")
At some point in the future, the Crystal Company begins to colonise Venus from their base at Terra Nova and is locked in conflict with the native lizards over the planet's valuable crystal orbs that can be used as a source of electrical power. Venus' atmosphere cannot sustain human life, although a human equipped with supplementary breathing apparatus may spend most of his or her time unmasked, requiring only occasional use of this equipment to survive. Parts of the planet are covered in thick jungle which becomes almost impassable after a rain. (: "In the Walls of Eryx")
In the far distant future, over half a billion years from the present day, the cosmic time traveller Titus Crow telepathically communicated with a species of intelligent mollusc which had evolved there. Ten million years after that, all life on Venus had been extinguished. (: The Transition of Titus Crow)
When Nathaniel Wingate Peaslee swapped minds with a member of the Great Race of Yith, one of the entities he met was a Venusian being "which would live incalculable epochs to come" (: The Shadow Out of Time). It's not known whether this Venusian was a member of the lizard-race, the intelligent mollusc race, or some other species entirely.
==Earth==
Earth is the third planet from the sun, and has been home to several native species throughout its colourful history.
Earth has also been colonised by numerous alien races, including but not limited to the Elder Things, the Cthulhi, the Outer Gods, the Mi-Go and the Flying Polyps. (: "The Dunwich Horror", "The Call of Cthulhu", The Whisperer in Darkness, At the Mountains of Madness, The Shadow Out of Time)
===Earth's moon===
Earth has a satellite, Luna, more often known simply as "the moon".
According to the Brick Cylinders of Kadatheron, the stone city of Ib and its misty lake inhabited by the Thuum'ha all descended to the land of Mnar from the moon in prehistory (: "The Doom That Came to Sarnath"). However, some accounts claim that the Thuum'ha didn't originate on the moon, but on a much more distant world (: Beneath the Moors, "Something in the Moonlight").
In the Dreamlands, the moon is habitable for humans and is inhabited by the hostile Moon-beasts. (: The Dream-Quest of Unknown Kadath)
The moon also has effects upon the Earth. Werewolves appear in nights of full moon (: "The Ghost-Eater"). Conversely, the Mi-Go prefer to avoid the moonlight altogether (: The Whisperer in Darkness).
The moon was formed when it was ripped off the Earth in the area that would later form the southern Pacific Ocean (: The Moon Pool, : At the Mountains of Madness, : The Transition of Titus Crow). In some accounts, it is claimed that the formation of the moon occurred before the Elder Things came to Earth and therefore long before the coming of the Cthulhi (: At the Mountains of Madness). However, other accounts claim that the Cthulhi were already present on Earth at that point and that some of them are still dormant inside the moon, which explains the historic association of the sight of the full moon and lunacy, due to the maddening effect these creatures have on the human mind, as well as being the reason that dogs howl at it (: The Transition of Titus Crow).
==Mars==
Mars is the fourth planet from the sun. With an atmosphere far thinner than our own, it is a land largely composed of barren red rock and sprawling Cyclopean ruins. (: "Through the Gates of the Silver Key")
It is still inhabited by the Aihai, a race of intelligent beings, and formerly the Yorhi, their antecedents. Other inhabitants include the Leeches of Yoh-Vombis, the Dweller in the Gulf, and the non-native Vulthoom. (: "The Vaults of Yoh-Vombis", "The Dweller in the Gulf", "Vulthoom")
==Asteroid Belt==
This was the remnants of a planet named Thyoph which used to orbit between Mars and Jupiter. (: In the Vaults Beneath) It was destroyed following a manifestation of Azathoth. (: Delta Green: Countdown)
Another source claims that, prior to its destruction, the planet was named Antanôk, and was home to a humanoid species which made contact with Earth, speculated to be the ancestors of modern humans (: "From the Parchments of Pnom"). These humanoids worshiped three extradimensional beings as gods, the mightiest of which was Pharol (: "Dust of the Gods").
==Jupiter (Ylidiomph)==
Jupiter is the fifth planet from the sun. Its Great Eye (actually a colossal storm system) is the prison of two of Cthulhu's "daughters", Nctosa and Nctolhu.
===Jupiter's moons===
Jupiter has several moons, including an outer moon which was inhabited by intelligent beings six million years ago (: The Shadow Out of Time), and a moon in which Randolph Carter witnessed some undisclosed horror (: "Through the Gates of the Silver Key").
The fourth moon of Jupiter is inhabited by a proud race of crawling Insect Philosophers. (: "Beyond the Wall of Sleep")
==Saturn (Cykranosh)==
Saturn is the sixth planet from the sun. This gas giant is a frequent refuge for practitioners of the dark arts. It is also called Cykranosh. (: "The Door to Saturn")
In ancient times, the planet was home to Tsathoggua. It has a counterpart in the Dreamlands, populated by monstrous cats. (: The Dream-Quest of Unknown Kadath)
The sorcerer Eibon used a portal to hide there from persecution by the cultists of Yhoundeh. It is the current home of Hziulquoigmnzhah and at least five sapient species: the Bhlemphroims, the Djhibbis, the Ephighs, the Ghlonghs and the Ydheems. (: "The Door to Saturn")
==Uranus (L'gy'hx)==
Uranus is the seventh planet from the sun. It is also called L'gy'hx and is home to the L'gy'hxians. (: "The Insects from Shaggai")
==Neptune (Yaksh)==
Neptune, a.k.a. Yaksh, is the eighth planet from the sun. This gas giant is inhabited by a strange species of fungoid creatures known as Yakshians, of which little is known. Several cosmic entities have made their home there over the aeons.
A race called the Neptunians or Yakshians dwells on Neptune. (: The Whisperer in Darkness, : "The Family Tree of the Gods") They might correspond to the spots of "hellish white fungi" that Randolph Carter observed on Neptune in his return to the solar system. (: "Through the Gates of the Silver Key")
For a brief period the Great Old One Hziulquoigmnzhah resided upon Yaksh after fleeing Yuggoth and the cannibalistic depredations of its parent Cxaxukluth. There it was worshiped by the Yakshians as a god, though it soon grew tired of these creatures and migrated to the planet Cykranosh. (: "The Family Tree of the Gods")
Later, Hziulquoigmnzhah's nephew Tsathoggua (who was also escaping Cxaxukluth's attentions) and a female entity named Shathak met, mated and spawned the creature known as Zvilpogghua on Yaksh. However, Tsathoggua moved to Cykranosh on his journey to Earth, and Zvilpogghua left our solar system entirely, making its way to the planet Yrautrom in the Perseus constellation (: "The Feaster from the Stars", "Strange Manuscript Found in the Vermont Woods"). Whether Shathak remains in residence on Yaksh is unknown.
==Pluto (Yuggoth)==
Pluto is a dwarf planet.
According to some accounts, Yuggoth, a colony of the Mi-Go in the solar system, is Pluto. (: The Whisperer in Darkness, : "Planetfall on Yuggoth")
Conversely, other accounts claim that Yuggoth is another planet, distinct from Pluto. (: "Discovery of the Ghooric Zone")
==Kynarth==
Kynarth is a world in the outskirts of the solar system, beyond Neptune and close to Yuggoth (: "Through the Gates of the Silver Key"). It might be the same as Kinarth. (: "On Icy Kinarth")
Category:Planets
Category:Locations Incorporated From the Real World
Category:Stars