The DS-2 Death Star II Mobile Battle Station, codenamed Second Sun, also known as the Death Star MK. 2, the Death Star Mark 2, or simply the second Death Star, was a partially completed moon-sized battle station constructed by the Galactic Empire as the successor to the first Death Star. A larger and more powerful Death Star, the second Death Star’s long-term purpose was similar to the first: to terrorize planets and star systems in league with the Rebel Alliance through the use of its planet-destroying superlaser. However, the Death Star II also served another purpose: luring the Rebels into a battle that would, the Empire hoped, destroy them once and for all. Though designed in the likeness of its predecessor’s appearance and function, the DS-2 Death Star saw a technical improvement through the incorporation of millions of millimeter-sized heat-dispersion tubes in place of the two-meter-wide thermal exhaust port exploited by the Rebel Alliance at the Battle of Yavin.

Secretly constructed in orbit around the remote forest moon of Endor, the Death Star II was larger than its 160-kilometer-wide predecessor and was constructed using more efficient methods. Positioned in synchronous orbit above Endor, the battle station was protected by a deflector shield projected by a ground-based shield generator, which used so much power that it was slowly destroying Endor. With the superlaser being the main priority, the weapon was completed by 4 ABY while the rest of the superstructure was still under construction. After the Empire secretly leaked the location of the «incomplete» second Death Star to Bothan spies working for the Rebellion, the Alliance Fleet arrived at Endor and were shocked to find the superlaser fully operational. In the ensuing battle, Rebel ground forces managed to destroy the shield generator protecting the Death Star, allowing Rebel starships to infiltrate the battle station’s reactor core and destroy the station. Combined with the deaths of Darth Sidious and his apprentice, the Sith Lord Darth Vader, the destruction of the second Death Star was a significant defeat for the Empire. Within a year, the fractured Empire formally surrendered to the Rebellion’s recently introduced government, the New Republic. Some of what little remained of the battle station fell on the waters of the ocean moon of Kef Bir.