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) and 'died': the Sun after this for a while left its course, burning a large part of Arda the world (apparently creating the deserts of Far Harad). In writings which are older than the material from which the published "Silmarillion" was drawn, the Moon was described at one point as being created by Morgoth as a mockery of Arda the world, but this notion was abandoned. In the Round World version of the legendarium, the Sun and the Moon were not the fruit of the Two Trees, but actually preceded the creation of the Trees. Instead, the Trees preserved the