I have one more thing to add: since the Death Star is the size of a small moon, and has docking bays open to outer space, how does the Empire keep the air from leaking out and escaping? You'll find the answer below.
Death Star = Death Trap
by Dan Vebber, in: Ted Edwards, The Unauthorized Star Wars Compendium, pp. 33-35, sidebars (formatting mine).
For all the yipping that Admiral Motti does about his station being the "ultimate power in the universe," certain aspects of the Death Star's construction leave a lot to be desired. Indeed, on several occasions the Death Star's sinister engineers seemingly designed things to be as dangerous as possible.
1 - THE SUPERLASER
Each of the superlaser's seven constituent beams shoots down a manned accelerator tunnel, causing anyone who might be standing next to these beams to shrink up against the wall and hope not to be disintegrated by a stray static charge. Each beam has at least enough power to destroy a planet one-seventh the size of Alderaan, so we can assume close-up exposure to any of them could lead to massive epidermal ionization, incurable melanoma, or at the very least, unwanted freckles. The superlaser accelerator tunnels probably have to be worker accessible -- and I'm not calling for removal of the catwalks along the beams' paths -- but couldn't they sufficiently warn the technicians before the thing was going to be fired so they could move out of harm's way? Would the installation of a few lousy warning lights really have cost that much more in the Emperor's grand scheme of things?
2 - DANGEROUS ALLOCATION OF UNWANTED GRAVITY
Any spherical battle station the size of a small moon would have its own gravity, wherein "down" would be directed toward the the station's center. But we can tell the Death Star uses artificial gravity generators, because "down" is always toward the station's "south pole." (Those Imperial boobs actually expend energy to defeat a core-oriented gravity situation that would have made more sense to begin with! Suckers!) Given that the station utilizes artificial gravity generators, why aren't they turned off or just plain not installed beneath the station's slew of virtually bottomless chasms? Countless stormtroopers (stormtroopers with families, I would remind you) would have lived to fight another day were their minor blaster wounds not followed by a plunge into oblivion.
3 - COMPLETE LACK OF SAFETY RAILS AROUND DEADLY CHASMS
Take docking bay 327, for example. There's a huge elevator shaft in the floor, in the middle of which is obviously a high-traffic area. And there's not so much as a Watch Your Step sign! Even more preposterous is the placement of controls for the tractor beam hundreds of feet up and surrounded only by a precarious six-inch-circular ledge. Sure, this setup worked to the Empire's advantage at least once, significantly slowing down Obi-Wan's attempt to sabotage the controls, but I'll bet the ratio of Rebel sabotage incidents to legitimate tractor beam maintenance by certified technicians wasn't low enough to justify the risky panel placement.
4 - UNPREDICTABLE, GUILLOTINE-SPEED PRESSURE DOORS
Sure, they look cool, but how many stormtroopers have to whack their heads running into rooms before the Emperor takes notice? We saw it happen once, and we were privy to only an hour or so of Death Star footage. Imagine what goes on during those thousands of hours we didn't see! How many concussions have occurred? How many slow-moving saps have been cut in half by the doors as they sliced down into the floor with the efficiency of a galactic-scale French Revolution? It is my hope and dream that one day the Emperor's dark servants will form a union and work to correct these flagrant safety violations.
Oh, wait, I guess it's only a movie. *