No, that's no moon.
It's the Sea-Based X-Band Radar, which is part of the U.S. defence Department Ballistic Missile defence System. It's a weird view, because usually—as you can see in the second image—it propels itself.
The platform—built by the Russians using a Norwegian twin-hulled oil platform design—is 380 feet long and 280 feet tall to the top of the main radar dome. Designed to work under any kind of weather, the 50,000-ton behemoth only moves a maximum of 10 degrees of its horizontal base using passive stabilisation.
According to Wikipedia, the SBX "has been moved to offshore Hawaii from its Aleutian Islands base in Alaska as of June 23, 2009. The reason: A potential North Korean missile launch that may hit the sea only 310 miles from US territory.
Yes, fun times ahead for Hawaiians. Maybe we should use one of these on Kim Jong Il's bunker before we get to some kind of point of no return. Although given their lousy track record, maybe we should just ignore that dumbass. [Wikipedia]