Space station. Not a moon...
The Death Star was the most powerful super weapon in the Galactic Empire's arsenal. It was a weapon of mass destruction and a doomsday device capable of destroying entire planets with a single powerful blast of its massive superlaser. It was meant to strike fear in the hearts of those who would dare to oppose the Empire.
The Death Star was an Imperial space station shaped like an artificial small moon. It was operated by thousands of Imperial personnel and had a massive complement of Imperial troops, vehicles and space craft on its many docking bays and hangars scattered across its main superstructure.
Its final design and construction were supervised by Imperial weapons designer, Raith Sienar, from original blueprints captured from Confederacy alien scientists and weapon designers who crafted them during the Clone Wars.