*Originally posted on AGU's Eos by Elizabeth Thompson
At the end of the 19th century, an astronomer named Percival Lowell first peered up at Mars and observed some dark lines with powerful implications--an extensive network of canals. He was thrilled to see what he considered evidence of an advanced civilization sculpting the Martian landscape as his fellow earthlings were constructing the Suez and Panama Canals.
Despite Lowell’s enthusiasm, these Martian canals were merely an optical illusion caused by the primitive telescopes of the day. But Giovanni Schiaparelli, the scientist who first observed the channels that Lowell interpreted to be canals, mapped out Martian seas and continents as well. Since his time, some studies have supported the idea that Mars had ancient oceans, long since dried up; others have challenged it.