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
Planet the Sun: Jupiter is the largest, at 318 Earth masses, whereas Mercury is the smallest, at 0.055 Earth masses. The planets of the Solar System can be divided into categories based on their composition: An exoplanet (extrasolar planet) is a planet outside the Solar System. In early 1992, radio astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsar PSR 1257+12. This discovery was confirmed, and is generally considered to be the first definitive detection of exoplanets. These pulsar planets are believed to have formed from the unusual remnants of the supernova that produced the