The Lost Worlds of Planet Earth Ortelius hypothesized the idea that land masses may have been connected in the past, Alfred Wegener who hypothesized the idea of a super-continent Pangaea and continental drift despite the prevailing idea of flooded land-bridges at the time, and Bruce C. Heezen and Marie Tharp who discovered the Mid-Atlantic Ridge that supported the theory of plate tectonics. Tyson describes how the landmasses of the earth lay atop the mantle, which moves due to the motion and heat of the earth's outer and inner core. Tyson moves on to explain the asteroid impact that initiated the Cretaceous–Paleogene extinction event, leaving small mammals
Super-Earth reported. Another Super-Earth, K2-155d, is discovered. In July 2018, the discovery of 40 Eridani b was announced. At 16 light-years it is the closest super-Earth known, and its star is the second-brightest hosting a super-Earth. The Solar System contains no known super-Earths, because Earth is the largest terrestrial planet in the Solar System, and all larger planets both have at least 14 times the mass of Earth and thick gaseous atmospheres without well-defined rocky or watery surfaces; that is, they are either gas giants or ice giants, not terrestrial planets. In January 2016, the existence of a hypothetical super-Earth-mass ninth