The Eclipse Cannon has not been shown in much detail, as it has only been shown from a distance while firing a blast. What can be seen is that it has four pieces surrounding the circular part where it fires its blast.
Features and abilities
The Eclipse Cannon is a weapon of incredible power, being capable of reducing half of the moon's surface to rubble in a single shot.
Some time in the past, the Eclipse Cannon got taken over by Dr. Eggman, who used it to blow up half of the moon.