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 a lower black body temperature than the more absorbent (lower albedo) Earth. Earth's magnetic field results from its flowing liquid metallic core, but in super-Earths the mass can produce high pressures with large viscosities and high melting temperatures which could prevent the interiors from separating into different layers and so result in undifferentiated coreless mantles. Magnesium oxide, which is rocky on Earth, can be a liquid metal at the pressures and temperatures found in super-Earths and could generate a magnetic field in the mantles of super-Earths. That said, super-Earth magnetic fields are yet to be detected observationally. According to one