(covers information from several alternate timelines)
|Satellites:||1 unnamed moon|
|Location:||Near the Romulan Neutral Zone|
Galorndon Core (often referred as the Galorndon Core) was a geologically unstable, uninhabited Federation planet. This planet was located 0.5 light years from the Romulan Neutral Zone. The atmosphere of the planet created severe electromagnetic storms that interfered with sensors and transporters; however, the atmosphere was capable of supporting humanoid lifeforms. The planet was located along a Barolian trade route.
In the alternate 2259, a mysterious wreckage was discovered on the mountainous surface of this planet. This event was reported in a news ticker, which was in a collection of graphics and video media that were seen on a powerwall in the offices of Christopher Pike and Alexander Marcus at Starfleet Headquarters. (Star Trek Into Darkness)
In 2366, the Romulan scout ship Pi crashed on this planet and the USS Enterprise-D was sent to investigate. The away team sent to the planet found the scout ship destroyed (deliberately, after it had crashed) and recovered a surviving crewmember. Unfortunately, Lieutenant Commander Geordi La Forge was trapped on the surface of the planet with another Romulan survivor, Centurion Bochra. Prolonged exposure of humanoids to the intense magnetic fields on Galorndon Core would result in synaptic breakdown. Bochra suffered from erratic metabolism and loss of sensation in his lower limbs, while La Forge became blind, even though his VISOR worked perfectly. (TNG: "The Enemy")
Background information Edit
"gal-OHRN-dan core" was the pronunciation for this planet's name from the script pronunciation guide for "Unification, Part II". 
For the remastered "Unification II", the appearance of Galorndon Core was corrected to how it appeared in "The Enemy". 
According to the Star Trek: Star Charts (pages 61 and 66), Galorndon Core was located in the Galorndon Core system. The system was located in the Beta Quadrant. This system was a single star system. Primary was a Class K star with a magnitude of +7, which was 1/10 brightness of Sol. In the mid-22nd century, this system was in or near Romulan space. After 2160, this system was in or near Federation space.
In the computer game Star Trek Generations, Galorndon Core was a major Romulan base of operations and the site of a secret launch point for Soran's weapon. The base was headed by a Commander Tala, who appears twice in-game and who was helping Soran synthesize trilithium from Galorndon Core I.
The Pocket ENT novel To Brave the Storm depicts Galorndon Core as a xenoecological paradise in the 22nd century until the Earth-Romulan War. In a manner similar to the Romulan attack on Coridan Prime (as depicted in Beneath the Raptor's Wing), a Romulan vessel intentionally collided with the planet's surface at high warp, causing a destructive global cascade that rendered the planet uninhabitable.
In Star Trek Online, Galorndon Core is located in the Narendra Sector of the Tau Dewa Sector Block. A pod of Gelki have gotten lost in the system; the player must lead them past Hirogen hunting parties and back to fluidic space.