Percival was born on the 13th of March 1855 and died on the 12th November 1916.
More than 110 years ago, he was an American businessman, author, mathematician, and astronomer. He was certain Mars was inhabited by intelligent life. And he set out to prove it. He developed his interest in astronomy as a student.
Lowell had become interested in what he thought were artificial canals on Mars. In 1894, Lowell used his money to build an observatory near Flagstaff in the clear Arizona sky. He set up two borrowed telescopes and set to work sketching the surface features of Mars, and he continued sketching and making measurements of Mars for more than 15 years. Not long after his first observations in 1894, Lowell loudly announced his discovery of canals on Mars, which he believed were created by the inhabitants of the Red Planet. They now believe the canals Lowell mapped were faint surface features and a bit of his imagination. Even though the canals were fake he remained at his telescope for the rest of his life, making drawings of Mars, as well sketching an early map of Venus. However what he saw on Venus was also probably not real since we know now Venus shows no surface features in visible light.
He predicted Pluto's existence in the 19th and early 20th century. In 1930 Pluto was discovered by Clyde Tombaugh at Lowell's Observatory. The name Pluto came from Percival's initials, PL.
Lowell also predicted a ninth planet, which he called Planet X. He thought a ninth planet existed based on strange patterns in the orbits of Uranus and Neptune. He searched for Planet X alone until his death in 1916. The observatory’s staff continued the search until 1930, when Clyde Tombaugh discovered Pluto at Lowell's Observatory. It turns out Pluto was too small to be Planet X, and the whole issue disappeared when, much later, an accurate discovery of the weight of Neptune showed the outer planets moved as known.