Glyth

Glyth was the sixth planet from the Sun in the Realms' solar system and was a bastion of the illithids. Seen from Toril, it looked like a dull gray orb surrounded by a spectacular ring and orbited by 3 smaller bodies. It was one of the Five Wanderers, the five superior planets of the Torilian solar system, which (from the perspective of Toril) seemed to defy the normal paths of the stars.

Geography
Glyth was a ringed planet approximately from the sun. It had 3 major satellites.

Glyth was a harsh planet, but only because of its inhabitants. What forests they did not have absolute control over they made sure were burned to the ground to prevent their humanoid cattle from hiding in them. This resulted in smoke filling the atmosphere which, in turn, nearly destroyed the atmospheric envelope and caused the planet to precipitate acidic rain constantly. The smoke caused the entire atmosphere to smell like a charnel house or a dead, burned forest. Of course, this didn't bother the mind flayers, who almost universally lived underground.

80% of the surface of Glyth was land while the other 20% was a strange gelatinous substance containing large amounts of water. The substance was edible and quenched thirst just like water would. It never turned brackish like normal water, nor did it ever freeze, remaining remarkably pure, despite the awful atmosphere. A sage who investigated the substance noticed that material that touched it was eventually sucked harmlessly right down to the bottom so that the substance remained on top. The poles of the planet were covered in regular ice, but the smoke stained it to look dirty.

Under the surface, the underground of Glyth was dominated by numerous mind flayer cities in a constant state of construction and expansion.

Glyth's planetary ring orbited the planet at the equator. During the day it looked like a beautiful, perfectly formed cloud with sharp edges but at night parts of it were colored in various soft oranges, reds and blues. Sometimes, the ring cast a slight shadow on the planet's surface during the day. From the ground, Glyth's satellites were reported as being attractive-looking as well.

Days were warm and lasted 30 hours and 30 minutes, but being on the surface ran the risk of getting hurt by the acidic rain that could burn the flesh of many creatures.

Haven
Haven was the smallest of Glyth's satellites, a hollowed-out asteroid that was used as a neutral meeting ground for rival illithid factions. Only illithid ships were permitted to enter the moon. A ship that did not belong to an illithid—and didn't have a very good reason to be there—was unlikely to ever leave again.

Haven was also the base for Glyth's security forces that patrolled the region around the planet for intruders. The mind flayers met there to trade, solve disputes and plan their expansion.

Mingabwe
Mingabwe was a small moon where all spacefaring races were welcome. It was almost empty, but it was the best choice for humanoid ships to land at if they did not want to risk the attention of the mind flayers.

Polluter
Pockmarked by asteroid impacts and with frozen water, but no atmosphere, this tiny moon orbited Mingabwe. Hidden somewhere on this moon were two evil magic items that belonged to Justin Demonslayer before he became a paladin.

The Rings of Glyth
Glyth had four rings made up of ice balls and small asteroids that orbited the planet's equator above the surface. The rings were thick at their widest and averaged out to  in most places.

The innermost ring was mostly ice, made dirty by smoke escaping the planet's atmosphere. It was separated from the second by the gravitational forces of the moon Haven.

The asteroids that made up the second ring had managed to arrange themselves according to color, having created a braided look to the ring.

The third ring was away from the second and was occupied by several large dark objects, none of which were smaller than  across. Rumors persisted that this was where Code Helm made their base.

The fourth and outermost ring, at its most distant extent from the planet's surface, was made up of tiny asteroids that got wedged together and formed lines that appeared as if they were wagon spokes. Each 'spoke' was separated from the next by thousands of miles.

The rings' moonlets were inhabited by several colonies of oortlings. Once captured from comets, they had been selectively bred by the illithids into a docile behavior.

History
Mind flayer refugees originally came from Glyth to Toril circa in their nautiloids and founded the city of Oryndoll.

However, sometime before, a sage who was an expert on illithids drilled into the ice of one of the poles and noticed that the mind flayers living on Glyth at the time had only been there for around a century.

During this period, the illithid population on Glyth was also constantly under attack by the Enforcers.

In the early 1360s DR, a group of scro survivors of the Second Unhuman War were captured by the illithids of Glyth, but their fate was unknown.

By the late 15 century DR, Glyth was still inhabited by illithid colonies. Captain N'ghathrod once lived in one such colony, before turning to a life of piracy aboard the Scavenger.

Inhabitants
Glyth's dominant inhabitants were illithids, who exerted almost complete control over the surface and most of the planet's underground. On the surface, the mind flayers used the remaining forests as huge ranches in which they kept humanoids as cattle. They referred to the humanoids as "skull cattle" and to the ranches themselves as Skull Sod.

The illithid selectively bred the humanoids in order to produce skull cattle of superior intelligence. The ranches, always kept on the move so the cattle lost its sense of direction, posed as advanced learning institutions in which the humanoids studied vigorously all their lives in preparation for the "outside world". In the late 14 century DR, the most prominent illithid ranch owner and humanoid breeder was Surrell, who was credited with the finest-tasting oortlings and was famous even outside Realmspace.

The remaining forests of Glyth were also inhabited by spider monkeys stolen from jungles of Toril. Their brains were considered delicacies and the monkeys attained a high price.

All non-illithid inhabitants and trespassers of the underground cities were enslaved by the mind flayers. The mind-controlled servants were frequently tasked with venturing to the desolate surface to gather resources, but were also sent to wage war against rival illithid cities.

In the late 14 century DR, a group of over 300 mercenaries from Code Helm resided near Glyth, conducting raids against illithids in the system. They were led by the paladin Easel Gifford of Amn.

Deep underground, below the caves inhabited by the mind flayers, a reclusive and mobile resistance organization consisting of an unknown number of humanoids called the Free Thinkers Union conducted raids against the illithids and attempted to liberate as many humanoid captives as possible. Resistance members were treated like vermin by the illithids, ruthlessly hunted down and killed.

Appearances

 * Adventures
 * Waterdeep: Dungeon of the Mad Mage (mentioned only)
 * Computer Games:
 * Spelljammer: Pirates of Realmspace