Formation and evolution of the Solar System impact event, the Tunguska event, the Chelyabinsk meteor and the impact feature Meteor Crater in Arizona. The process of accretion, therefore, is not complete, and may still pose a threat to life on Earth. Over the course of the Solar System's evolution, comets were ejected out of the inner Solar System by the gravity of the giant planets, and sent thousands of AU outward to form the Oort cloud, a spherical outer swarm of cometary nuclei at the farthest extent of the Sun's gravitational pull. Eventually, after about 800 million years, the gravitational disruption caused by galactic tides, passing stars
Sun and Moon (Middle-earth) an immense island of fire. The Moon was described as an immense island of crystal. It was also said there that the youth Tilion, who guided the Moon, was said to secretly be in love with Arien, the maiden who guided the Sun, and that because he steered the Moon too close to the Sun the Moon was burned, causing the darker spots on the Moon (the Lunar maria). Aulë devised "vírin", a crystalline material from which he made a cup wherein the flower was set. The markings on the moon are caused as Lórien tried to pluck the "Rose