Percival Lowell was born in 1855 to a distinguished New England family. His younger brother was president of Harvard University and his sister was a well-known writer. Lowell also attended Harvard and graduated in 1876 with a distinction in mathematics. After traveling in the Far East for a number of years, he eventually developed a fond interest in astronomy. He was particularly interested in Mars and its "canals" that had supposedly been discovered by the Italian astronomer, Schaparelli.
In 1894, Lowell founded the Lowell Observatory in Flagstaff, Arizona. The observatory was ideally situated at an altitude of 7000 feet. The high altitude combined with the dry desert air made this site ideal for observing Mars, which was at that time very close to the Earth. Lowell observed the red planet for 15 years. He made intricate and detailed drawings of the planet's surface showing a complex network of intersecting lines and dark regions. Lowell believed these lines to be canals built by an advanced civilization of intelligent beings. He asserted that these canals were being used by a desperate race to transport precious water from the planet's icy poles. The dark regions were believed to be oases of green vegetation made possible by the irrigating canals. Lowell published these theories in three books: Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). Today we now know that these "canals" are merely optical illusions caused by the turbulent atmosphere and the human eye's natural tendency to "connect the dots" on the planet's dark regions.
Aside from his detailed observations of Mars, Lowell's greatest contribution to the field of astronomy was made during the last eight years of his life. He was the first to realize the discrepancies between the calculated and observed positions of Uranus and Neptune. He believed that a ninth planet beyond the orbit of Neptune was responsible for the anomalies. He began to examine photographs of the regions of sky where he suspected the new planet might be found. He searched in vain for the new planet until his death in Flagstaff at in 1916. The search for the ninth planet continued for several years after Lowell's death. In 1930, the planet Pluto was finally discovered by Clyde Tombaugh. This discovery might not have been possible if it were not for the pioneering work of Lowell and his observations of the outer planets. Though this was his greatest contribution, he is still more well known for his theories and writings about the famous Martian canals.