Eclipse Cannon

The Eclipse Cannon is an ultimate weapon of mass destruction on the Space Colony ARK, able to destroy planets and pierce stars. The Chaos Emeralds are needed for the cannon, as it takes large amounts of energy to power it. The Cannon can be seen on the outside of the ARK as it forms the nose of the research center.

While the Eclipse Cannon never reached its full potential, using only five emeralds, it is capable of destroying a large city and produce a large dent in a planet. With six emeralds, it is able to destroy half a moon.

Sonic Adventure 2
The Eclipse Cannon was first introduced to Eggman by Shadow to grant his one wish of world conquest. Shadow explained that all seven Chaos Emeralds were needed to fully power the weapon. The two of them, with the government spy Rouge, who was sent there to gather information about Shadow, gathered a total of five emeralds (one Eggman already had, one Rouge offered to join up, the one that Shadow stole, and three stolen from G.U.N.). Eggman then used the cannon to destroy half of the moon to terrorize Earth into submission. However the demonstration proved to have flaws. With the cannon requiring 24 hours to charge due to not having all the emeralds, Sonic and his friends were able to penetrate the ARK and stop the cannon before it fired again. Eggman, who was apparently unaware of what happened, installed the last emerald he took from Tails. A hologram of Eggman's grandfather Gerald Robotnik appeared, which revealed that he secretly downloaded a doomsday device that activated when the seven Chaos Emeralds were brought together. With the immense energy being moved to the cannon's core, the ARK was sent on a collision course to Earth. When Knuckles and Sonic bring the Master Emerald to the core, it turns out to be a shrine similar to the one on Angel Island, designed to maximize the emeralds' power. Shadow defeated the Biolizard, and they managed to control the Chaos Emeralds. Despite this, the ARK was still crashing to Earth. Eggman revealed that the prototype had used Chaos Control to attach itself to the exterior of the ARK, pulling it towards the planet. Shadow and Sonic used the Chaos Emeralds to transform into their super forms. They fought and defeated the "Final Hazard," as it fell to Earth. Though, in order to stop the ARK from falling, the two used Chaos Control to bring it away from the planet's atmosphere. Due to exhausting his powers by teleporting the space colony, Shadow crashed to Earth. Sonic returned to the control room with his ring and told everyone what happened. As they all left the ARK, Sonic looked back and said, "Sayonara, Shadow the Hedgehog."

Shadow the Hedgehog
After the events of Sonic Adventure 2, the Cannon was apparently repaired by G.U.N. The military also deployed robots to guard the control room. During a possible Dark Side storyline, the Eclipse Cannon and the ARK were later to become under control of Black Doom and the Black Arms (with the assistance of Shadow), who wanted to use the cannon to take control of Earth. With five emeralds, the cannon destroyed the White House and Central City. During the Last Story when Shadow was fighting Black Doom, a hologram of Gerald revealed to Shadow that the cannon was developed to destroy the Black Comet. The cannons purpose was fulfilled after Black Doom was defeated by Super Shadow. Shadow used Chaos Control to teleport the comet into outer space and fired the cannon to destroy the comet. After the last story was over, Shadow said,"Sayanora, Shadow the Hedgehog and wanked for joy."