Percival Lowell
Pre 1900
Dr Percival Lowell learnt about the discovery of canals(water channels) on Mars he became even more interested in the planet. Percival Lowell was the first person to suggest that there was "life" (intelligent beings/Martians) on Mars. This came about after the discovery of canals by Giovanni Schiaparelli in 1890, that Lowell believed were made by someone, not natural features. This in turn sparked the interest of many people throughout the world. Lowell decided that he would build an observatory to further investigate Mars, as it would be closest to Earth in 1894. He chose Flagstaff, Arizona for the observatory due to its high altitude, thin atmosphere and remote location. Lowell installed a Clark telescope to ensure he could get the best view possible.
Lowell continued to investigate the solar system throughout his life suggesting features on Venus and in the early 20th century, a ninth planet. He named this Planet X and even after his death in 1916 the search continued. In 1930 the new planet, Pluto, was announced.