Martian Martian A Martian is a native inhabitant of the planet Mars. Although the search for evidence of life on Mars continues, many science fiction writers have imagined what extraterrestrial life on Mars might be like. Some writers also use the word "Martian" to describe a human colonist on Mars. The earliest known instances of the word "Martian", used as a noun instead of an adjective, were printed in late 1877. They appeared nearly simultaneously in England and the United States, in magazine articles detailing Asaph Hall's discovery of the moons of Mars in August of that year. The next event
Planet the latter half of the 20th century of more objects within the Solar System and large objects around other stars, disputes arose over what should constitute a planet. There were particular disagreements over whether an object should be considered a planet if it was part of a distinct population such as a belt, or if it was large enough to generate energy by the thermonuclear fusion of deuterium. A growing number of astronomers argued for Pluto to be declassified as a planet, because many similar objects approaching its size had been found in the same region of the Solar System