Martian Earth, but faced a process of devolution as conditions on the planet worsened. "Quatermass and the Pit" (1958–59) is a British television serial in which a crashed spacecraft is discovered in London. The wreck evidences that the human population of Earth resulted from the experiments of a Martian civilisation, now long dead. A film remake was released in 1967. "Ghosts of Mars" (2001) human invaders war with Martians in an attempt to conquer Mars. In the "Invader Zim" episode "Battle of the Planets" (2001), Zim discovers that a Martian race died off after converting Mars into a giant spacecraft. In
Solar System known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way galaxy. For most of history, humanity did not recognize or understand the concept of the Solar System. Most people