Caption: Percival Lowell (1855--1916), a member of the famous Massachusetts Lowell family, was one of the last great astronomer magnates---others of his ilk are Alonso the Wise (1221--1284), Ulugh Beg (1394--1449), Tycho Brahe (1546--1601), and William Parsons, 3rd Earl of Rosse (1800--1867).

Features:

1. Lowell was an enthusiastic promoter of the Martian canal theory and did many observations from his own Lowell Observatory, founded 1894 in Flagstaff, Arizona---that is to say the thing a mile away just up the hill from Northern Arizona University (NAU) where yours truly worked 2010--2011.

2. Lowell drew many maps of Mars detailing the Martian canals that he thought he could make out from visual astronomy.

3. In reality, the Martian canals were almost entirely optical illusions caused by the human eye trying to make out shapes in variations in color at the limit of visual perception.

   Only one "canal" feature, a giant canyon Lowell named Agathodaemon (after the Greek god Agathodaemon), turned to be real: it is now called Valles Marineris after the Mariner 9 probe (1971--1973) that really discovered it (No-578).

4. Lowell did believe that the Martian canals were artificial and a product of intelligent Martians

5. You may well ask why Lowell did NOT use astrophotography which was nearly as old photography---the first astrophotography attempts occurred as early as 1839.

   Astrophotography was too long-exposure and/or too slow in action in those days to catch Mars in still air when the astronomical seeing was good and Mars was sharply focused. Remember, Mars is quite a small object in angular diameter, and so relatively small, rapid fluctuations of turbulence in the air can blur it in astrophotography.

   Lowell and other visual astronomers waited for the still air moment and then drew from memory (Wikipedia: Martian canals: History of canals).

6. Actually, many astronomers contemporary to Lowell NEVER believed in the Martian canals being aware of the difficulties in observing at the limit of visual perception. Lowell rebutted them by saying he had the best observing site in the world at that time, and so he could potentially do better visual astronomy than anyone else. This was true, but Lowell was still observing mostly optical illusions and NOT observing Martian canals.