Ilum, a planet blanketed in snow, was situated in the 7G sector of the Unknown Regions, specifically within the Ilum system. Orbiting the blue dwarf star Asar as its fifth planet, Ilum maintained a roughly equal distance from Asar and the system's cometary cloud. Possessing a kyber crystalline core, Ilum served as a crucial site for the Gathering, a long-standing Jedi Order tradition spanning millennia, where Jedi younglings sought and procured kyber crystals to construct their personal lightsabers.
Following the extermination of the Jedi Order under the command of Darth Sidious, as per order, the newly formed Galactic Empire seized control of Ilum. They initiated extensive mining operations to extract the abundant kyber crystals, intending to utilize them in the construction of the first and second Death Stars. This excessive exploitation of the planet led to the formation of a massive Imperial Trench along Ilum's equator, destabilizing its core.
After the Empire's downfall, the First Order, its successor, transformed the vast trench into Starkiller Base. This system-destroying superweapon represented the culmination of Imperial research into dark energy translations and hyperspace tunneling. Kept secret by the First Order, Ilum's modifications enabled it to function as a mobile base and powerful weapons platform. Ultimately, it faced destruction at the hands of the Resistance, who desperately acted after Starkiller's destruction of the Hosnian system. The attack was led by Poe Dameron. The planet then collapsed into a star, later christened Solo in honor of the legendary smuggler Han Solo, who perished on Ilum.
Ilum, though smaller than a dwarf planet, was a terrestrial celestial body. Its icy climate and kyber crystalline core earned it the classification of a planet, despite its diminutive size. It resided in the eponymous star system, situated within the 7G sector of the Unknown Regions. As an arctic world, Ilum was almost entirely covered in ice and snow, making it largely uninhabitable for most species. However, it did support a population of non-sentient creatures.
Beneath Ilum's frozen surface lay the Crystal Cave. This intricate network of caves was home to kyber crystals, attracting the Jedi Order for the rite of passage known as the Gathering. During this ritual, Jedi initiates would attune themselves to the Force to find and harvest their crystals. Consequently, Ilum held immense significance as a sacred site for the Jedi Order for countless centuries.
Also situated below Ilum's surface were geysers, products of the planet's volcanic activity. These geysers warmed subterranean bodies of water, and their size and activity varied due to volcanic events and mineral accumulation. The caves also featured geological formations, shaped over billions of years by the deposition of mineral matter from hydrothermal fluids.
By 18 BBY, the Empire had already begun its destructive exploitation of Ilum, depleting its resources and devastating its surface. This damage was evident even from space. When Great Jedi Purge survivor Ahsoka Tano revisited the planet, she observed the presence of at least two Star Destroyers and a mining ship in orbit. Large sections of the planet had been removed, exposing the underlying rock and [magma](/article/magma] rising from its core.
The recorded history of Ilum begins several thousands of years prior to the Galactic Empire's creation. Shortly after the formation of the Jedi Order on Ahch-To, a Jedi scout utilized the Force to navigate hyperspace routes through hyperspace, which led her into the Unknown Regions. She was drawn to a powerful Force resonance, which guided her to Ilum. The scout reported that Ilum lacked sentient life but was abundant in non-sentient animals.
Subsequent survey teams discovered significant quantities of naturally occurring kyber crystals, including pontite and mephite. The Jedi Order's High Council dispatched scholars, artisans, and warriors to secure the planet. The Council decided to keep the planet's existence a secret from the galaxy. Hyperspace surveyors charted a direct, albeit complex, hyperspace route from the Core World of Metellos to Ilum. Eventually, all references to Ilum were erased from local, sector-wide, and galactic star maps. The Jedi rogue Deelguh once led his forces in a raid on Ilum, where they clashed with defenders under Deelguh's old Jedi training comrade Taradon. Taradon sacrificed himself to take out Deelguh by crashing his starfighter into Deelguh's own craft.
The Jedi Temple on Ilum, nearly completely covered in ice, remained the only sign of intelligent life. The Jedi removed all other bases from the planet. As other planets depleted their kyber crystal reserves, Ilum became an increasingly important source. Traditionally, Jedi younglings would travel to Ilum aboard the Crucible, escorted by a senior Jedi, to construct their first lightsabers. According to a forgotten legend, at some point Sith may have laid siege to the world, eventually taking possession of it for a time.
When Jedi youngling Enya Keen visited Ilum during the High Republic Era, she focused her senses on finding a kyber crystal that would call to her as she carefully made her way through the Crystal Caves. Eventually, a specific crystal called out to her from a three-meter chasm. Although she sustained cuts during her trek down, she recovered the crystal, which would shine in a nearly golden-yellow light. To Keen, the light was as if the crystal was happy to finally meet her and ready to begin their journey, with Keen unsure of what that journey would entail at that time. However, she came to understand that journey was the crystal helping in her Jedi duties and communing with the Force in new ways.
Four months after the Clone Wars began, Jedi Master Luminara Unduli took a break from the fighting to accompany her Padawan, Barriss Offee, to Ilum to assist her in building a new lightsaber. During their time on Ilum, chameleon droids attacked the temple; however, Grand Master Yoda intervened and saved them. In 20 BBY, a Gathering took place during the war. Padawan Ahsoka Tano escorted the younglings Byph, Ganodi, Gungi, Katooni, Petro, and Zatt to the Crystal Cave, where Yoda awaited their arrival. Each youngling faced unique challenges in order to obtain their crystals.
Afterward, all of the younglings departed Ilum aboard the Crucible, where the architect droid Huyang instructed them on how to construct their lightsabers.
When Order 66 was initiated, the clone troopers of the 481st Legion were dispatched to Ilum to eliminate any surviving Jedi hiding there.
In 18 BBY, the Galactic Empire claimed the Jedi world after it was located by Palpatine's deep space expeditions into the Unknown Regions, which utilized ancient navigational routes discovered within the Jedi Temple. The Empire invaded, quickly occupied, and began strip-mining Ilum as part of a large-scale terraforming project. The Empire harvested the small world's abundance of energy-focusing kyber crystals for the focusing arrays of the Death Stars' superlasers, thus revealing magma bubbling from Ilum's core. The entrance to the Jedi Temple was destroyed to allow access to the crystal caves. The Empire dug a massive mining ship into the world as part of the effort to gain its riches. At least two Imperial Star Destroyers stood watch over the planet.
The Empire's mining effort did not show respect to Ilum as the Jedi had, leaving the world ravaged and making surviving Jedi despair for the loss of many kyber crystals, which no longer sang in the Force. Nevertheless, lower concentrations of crystals still existed elsewhere in the galaxy, ready for anyone who was willing to listen for their call. The Empire used geothermal energy from the planet's core to power their machinery and control the internal temperature of their industrial operations. Harmful byproducts were created as a result, causing destruction to Ilum's pristine ecosystem. Eventually, a large industrial equatorial trench, called the Imperial Trench, was realized over the planet as part of Imperial plans, replacing what were gaping cracks that struck into the planet core of kyber.
After his lightsaber was severely damaged, the Padawan Cal Kestis visited Ilum's Jedi Temple to find a kyber crystal in the crystal caverns of the world and build a new lightsaber. Although he had problems with the Imperial garrison on the planet, he was successful in his mission and able to escape the planet.
During the Imperial Era, Imperial scientists undertook a mission to Ilum.
Sometime after the Battle of Hoth, Jedi-in-training Luke Skywalker visited Ilum in search of knowledge about the Jedi to complete his training. However, upon seeing the Imperial presence and what they had done to the world, Skywalker changed his mind. He felt that the place had been important to the Jedi in the past, but now there was only pain. Skywalker left the place after realizing there was nothing there for him.
After the Battle of Jakku, a select number of "worthy" officers and personnel disappeared into the Unknown Regions and reorganized themselves into the First Order. Ilum was chosen to begin development of the Starkiller project by the First Order, and over the 30 year period they continued the excavations started by the Empire, transforming the equatorial trench into a superweapon, Starkiller Base, with the planet's kyber crystalline core serving as the containment field for the base's main weapon.
By 34 ABY, the First Order would use the Starkiller Base to destroy the Hosnian system. The Hosnian Cataclysm destroyed the New Republic, and the Resistance, acting on intelligence obtained from Finn, a defected First Order stormtrooper, launched an attack on Starkiller Base in an attempt to destroy the superweapon before it could fire on their base at D'Qar. Ilum was mobilized to the Starkiller Base system, whose star it then drained to recharge its weapon.
With help from Han Solo, Chewbacca, and Finn, who arrived on Ilum to disable the shield protecting the planet, the Resistance was able to destroy the thermal oscillator that prevented the Starkiller weapon from destabilizing. The destruction of the thermal oscillator caused a chain reaction of explosions across Ilum's surface, and Ilum imploded and exploded, becoming a miniature star which became known as "Solo."
Ilum's most prominent feature was its Jedi temple, concealed beneath a large ice cliff. Below the temple lay a vast network of crystal caves, rich in kyber crystals and serving as the site of the Gathering. The remainder of Ilum's surface was largely barren, featuring canyons, mountains, ice fields, and some forests.
Ilum made its initial appearance in Star Wars canon in "The Gathering," the sixth episode of the fifth season of the animated television show Star Wars: The Clone Wars, which aired on November 12, 2012. The planet originated in Star Wars Legends, debuting in the junior novel Jedi Quest: Path to Truth, released on September 1, 2001. In visual media within Legends, it appeared in Chapters 14-16 of Star Wars: Clone Wars, broadcast on Cartoon Network in 2004.
The 2019 video game Star Wars Jedi: Fallen Order depicts Ilum in a manner similar to Starkiller Base. This depiction is also present in the 2017 reference book Star Wars Super Graphic: A Visual Guide to a Galaxy Far, Far Away. Furthermore, the book specifies Ilum's diameter as 660 kilometers, matching Starkiller Base's diameter. The connection between Ilum and Starkiller Base was officially confirmed in Star Wars: The Rise of Skywalker: The Visual Dictionary.