According to the nebular theory, what are asteroids and comets? They are leftover planetesimals that never accreted into planets They are the remmants of collions between moons They are remnants of collisions between planets They are chunks of ice and rocks that formed long after the planets had accreted. Water that currently exists on Earth's surface probably originated with the giant impact that formed the Moon with comet impacts with chemical reactions that occurred as the Earth cooled with ice that condensed in the region of the nebula where Earth formed Which of the following predictions is not supported by the nebular theory differences in composition between terrestrial and Jovian planets planets orbiting the Sun in nearly circular orbits equal numbers of Jovian and terrestrial planets craters on Mercury.