The Lost Worlds of Planet Earth The Lost Worlds of Planet Earth "The Lost Worlds of Planet Earth" is the ninth episode of the American documentary television series "". It premiered on May 4, 2014 on Fox, and aired on May 5, 2014 on National Geographic Channel. The episode was directed by Brannon Braga, written by Ann Druyan and Steven Soter, and featured the voice of Amanda Seyfried as geologist Marie Tharp. The episode explores the history of the Earth starting with the period of the Late Heavy Bombardment, approximately "3.8 to 4.1 Billion years ago during which the Moon, Mercury, Venus, Earth and were battered
Planet speed, because it is less affected by its star's gravity. No planet's orbit is perfectly circular, and hence the distance of each varies over the course of its year. The closest approach to its star is called its periastron (perihelion in the Solar System), whereas its farthest separation from the star is called its apastron (aphelion). As a planet approaches periastron, its speed increases as it trades gravitational potential energy for kinetic energy, just as a falling object on Earth accelerates as it falls; as the planet reaches apastron, its speed decreases, just as an object thrown upwards on Earth