The Ocean Worlds Of Our Solar System. There are more than 100 moons in our Solar System that do their mysterious gravitational dance around the eight major planets belonging to our Sun's family. Most of them are icy and small, containing only tiny quantities of rocky material, and they circle around the quartet of giant gaseous planets that dwell in the outer regions of our Solar System. The four majestic, giant denizens of the outer limits--Jupiter, Saturn, Uranus, and Neptune--are cloaked in blankets of gas, and they are orbited by sparkling, icy moons and moonlets. Of the quartet of relatively small, rocky terrestrial planets--Mercury, Venus, Earth, and Mars--Mercury and Venus are moonless, and Mars is circled by a pathetic duo of tiny and somewhat deformed moons (Phobos and Deimos). The two little moons of Mars are interesting objects, frequently considered to be asteroids that escaped from the Main Asteroid Belt between Mars and Jupiter, only to be snared by the Red Planet's gravitational pull when our Solar System was young. Earth's own beautiful, beguiling, bewitching Moon is the only large one inhabiting the inner kingdom of our Solar System. This cycle has been appropriately named the 'dark moon'. The cycle from one dark moon to the next is called a lunation and an average lunation calculates at about 29 days, 12 hours, 44 minutes and 3 seconds (roughly) To be fair, it does deviate in relation to the moons erratic orbit patterns and is affected by the gravity conflict between the sun and the moon. There was a time when Earth had no Moon. About 4.5 billion years ago, when our ancient Solar System was still forming, the dark night sky above our primordial planet was moonless. At this time, the Earth was about 60 percent formed, although it did have a differentiated crust, mantle, and core. This was a very chaotic and violent era in our Solar System's past, with planets first forming out of blobs of primordial dust, gas, and rock. During this era, frequently likened to a "cosmic shooting gallery", collisions between the still-forming planets were commonplace. Orbits were not as orderly as they are now.