Future of Earth Sun. The drag from the solar atmosphere may cause the orbit of the Moon to decay. Once the orbit of the Moon closes to a distance of , it will cross the Earth's Roche limit. This means that tidal interaction with the Earth would break apart the Moon, turning it into a ring system. Most of the orbiting ring will then begin to decay, and the debris will impact the Earth. Hence, even if the Earth is not swallowed up by the Sun, the planet may be left moonless. The ablation and vaporization caused by its fall on a decaying
Discourse on the Tides is the motion of water relative to the earth, but annual revolution is the motion of the earth, and its water, relative to the sun. Annual revolution results in a force that accelerates the earth-water system but does not accelerate the water relative to the earth, in the same way that an observer standing on Earth's surface does not feel the gravitational attraction of the sun because the observer and Earth are moving together around the sun. The discourse does not include gravitational forces in its theory to explain the Earth's orbit and does not consider the relation between the