Mars is one of the naked eye planets and
is often one of the brightest objects in
the sky, so its
existence has been known for thousands of years.
In the late 1800s, Giovanni Schiaparelli made
telescopic observations of Mars and drew a series
of lines on the surface of Mars based on what
he (thought he) saw. He called these lines canali
which in English is "channels" but has often been
mistranslated as "canals."
The thought of channels -- or even more excitingly
canals -- on Mars drove speculation and the search
for more details about Mars and the possibility
of life on Mars.