Hosnian Cataclysm

"This fierce machine which you have built, upon which we stand, will bring an end to the Senate, to their cherished fleet. All remaining systems will bow to the First Order and will remember this as the last day of the Republic!"

- General Hux

The destruction of the Hosnian system occurred three decades after the Battle of Endor. Immediately prior to the Battle on Takodana, General Hux of the First Order tested the power of the Starkiller Base on the Hosnian system. The Hosnian system hosted the capital of the New Republic, Hosnian Prime, as well as the New Republic Starfleet.

After gaining Supreme Leader Snoke's permission to fire the superweapon, Hux chose the heart of the New Republic to demonstrate the power of the First Order in an attempt to wipe out the "illegitimate" government of the New Republic in one fell swoop. The test was a success and Hosnian Prime, home of the Galactic Senate, all other astronomical bodies in the system, and an unknown percentage of the New Republic fleet were annihilated by the First Order's superweapon.

Because the Starkiller's beam travelled through a torn portion of space-time whose properties were not fully understood, the destruction of the Hosnian system was visible from the surface of Takodana.

Behind the scenes
The fact that the blast from Starkiller Base could be immediately seen from Takodana, despite being many light-years away from the Hosnian system, has been pointed out by some viewers as a violation of general relativity. Pablo Hidalgo of the Lucasfilm Story Group suggested that the beam could be seen from Takodana due to a "hyperspace-rip side-effect" of the Starkiller.

Appearances

 * Star Wars: Episode VII The Force Awakens