What'll happen if gravity suddenly disappeared? The followin things would happen almost immediately: 1. The earth would no longer orbit the sun. Instead it would continue in a straight trajectory starting from the point it occupied when gravity disappeared. This is because the sun would no longer be exerting gravity on the earth and causing it to fall towards the sun in its orbit 2. The moon would wander off in the same way. It is possible that the earth and the moon would collide depending on their relative positions and trajectories when gravity disappeared. 3. The atmosphere and water etc would quickly fly off into space. For a time, the atmosphere would stay with the earth because most of the atmosphere would be travelling in the same relative direction and the same relative speed as the earth.. 4. the Sun would bling out. Currently the fusion reaction which lights the sun is maintained because the gasses are compressed to an unbelievable extent at the core of the sun. Without gravity, there would be insufficient pressure to maintain an atomic reaction..