The circle with the ring is a comet with a large coma. As the comet moves, the coma loses dust and gas to the tail and then into space to form a faint trail. The curved line beneath the comet  traces the trail of the coma from its beginning on the right to the time of the crop circle. On the left  the comet is passing a planet, probably Earth, on its way around the Sun and back again for final impact.