“What [Isaac] Newton helped us figure out with classical mechanics is that the pieces accumulating and moving closer together would release some of their own energy, heating things up,” Zimbelman said.
Think of it like a meteorite streaking across the sky. The remnants that ended up in the far reaches of the atmosphere and outer space would be drawn to the surface by the planet’s gravitational pull, and they would release energy upon impact. The constant bombardment of these bits and pieces would liquefy the crust into a molten “ocean of rock,” Zimbelman said. Eventually, colliding fragments would be reabsorbed into the molten sea through a process called accretion.
According to Zimbelman, the rapid and destructive transition would also vaporize most of the water on the planet’s surface. While most of this vaporized water would be lost, some might be incorporated into newly solidified minerals, like olivine. Finally, not all of the fragments would be reabsorbed through accretion. Some of the planetary bits would be swept up by the moon’s gravitational pull, bombarding the nearby satellite and creating countless more craters across its surface.