Space Colony ARK had caused damage to the moon when it fired its six Chaos Emerald-empowered Eclipse Cannon, the beam hit the moon causing the half of it to explode. Later on after the events, Doctor Eggman, while trying to convince everyone that he had changed his evil ways, offered to repair the damage done by launching a mini-missile which replaced the missing half of the moon with a self-replicating metallic half in order to return the moon to its original shape. This then caused the moon to be placed in a solar eclipse on New Years Day at sunrise. In order to solve the problem of a world bathed in darkness, Eggman invented the Sunshine Ball, in order to provide the world with light for the next few months it would take to repair the Egg Moon's software and pull it out of the eclipse.
A few weeks into this however, Sonic the Hedgehog began to smash the energy towers that the reflected sunlight was being channeled into, causing serious problems for the humans and turning him into a public enemy as a result of his actions, only for Sonic to state that the Egg Moon was being deliberately placed in front of the sun, explaining that if the Egg Moons ability to go around the Earth was stopped, it would just stay in the same place in its orbit while the Earth traveled in its own rotating orbital pattern around the Sun. At the same time, Rouge and Topaz both discovered a hidden facility that was transmitting a control signal to the Egg Moon prompting an explanation from Eggman. Eggman planned on converting humanity to his side so their would be minimal resistance for when he kidnapped the president so he could create his Eggman Empire, however his plans were foiled by the combined efforts of Sonics Friends and Stuart who managed to free the president and send Eggman and his minions on the run. While up in space, Knuckles destroyed the reciever on the Egg Moon, allowing it to continue in its orbit and go out of the eclipse, finally bringing sunlight back to Earth again while Eggman, Decoe, and Bocoe were arrested and sent to prison.
Sonic the Hedgehog 4Edit
The Egg Moon returns in Sonic the Hedgehog 4 when Doctor Eggman offered to clean Sector Z by launching two mini-missiles which absorbed a graveyard of wrecked warships (along with a large base and multiple wings of starfighter defenses) with a self-replicating metallic sphere in order to create an artificial moon in the same size of the Little Planet. The Egg Moon was mechanized to make a new version of the Death Egg, which can be seen in Act 3 and the boss act of Sylvania Castle Zone and boss act of White Park Zone. The new Death Egg is a hollow sphere built above and around the Egg Moon similar to a Dyson sphere, the hypothetical Dyson sphere is designed to absorb energy from a star; this, presumably, is also the method which Eggman uses to power his latest space station.
- In Sonic X, the Egg Moon resembles the Death Egg, except it's only half mechanical and it doesn't have Doctor Eggman's face until it is now fully mechanical in Sonic the Hedgehog 4.