Saturn
Saturn is the sixth planet in the solar system, and the second largest gas giant. Saturn's rings are littered with a number derelict ships of the Golden Age, including the Cassini. The City has yet to make contact with Saturn due to its great remoteness, but the Nine seem to have some claim over Saturn's moons.
In The Taken King, the Hive Dreadnaught, the fortress of Oryx, is found orbiting Saturn, between its "B" and "C" rings.
Trivia
It should be noted that Saturn's middle or "B" Ring is, in fact, much denser than the inner "C" and "D" rings, which means that Saturn would not be visible through it, as erroneously indicated in the fourth image in the gallery below. The fact that the "B" ring appears darker is due instead to the player approaching from the unlit side. Based on the width of the "C" ring (approx 17500 km), we can deduce that the blast radius of the weapon is in the vicinity of 15,000 km.