From "Death by Black Hole and Other
Cosmic Quandaries" by Neil DeGrasse Tyson
Lowell
maintained that Venus sported a network of massive, mostly radial spokes (more canali) emanating from a central hub. The
spokes he saw remained a puzzle. In fact nobody could ever confirm what he saw
on either Mars or Venus. This didn't much bother other astronomers because
everyone knew that Lowell's
mountaintop observatory was one of the finest in the world. So if you weren't
seeing Martian activity the way Percival was, it was surely because your
telescope and your mountain were not as good as his.
Of course, even after telescopes got better, nobody could
duplicate Lowell's
findings. And the episode is today remembered as one where the urge to believe
undermined the need to obtain accurate and responsible data. And curiously, it
was not until the twenty-first century that anybody could explain what was
going on at the Lowell Observatory.
An
optometrist from Saint Paul,
Minnesota, named Sherman Schultz
wrote a letter in response to an article in the July 2002 issue of Sky and Telescope
magazine. Schultz pointed out that the optical setup Lowell preferred for viewing the Venutian surface was similar to the gizmo used to examine
the interior of patients' eyes. After seeking a couple of second opinions, the
author established that what Lowell saw on
Venus was actually the network of shadows cast on Lowell's own retina by his ocular blood
vessels. When you compare Lowell's
diagram of the spokes with a diagram of the eye, the two match
up, canal for blood vessel. And when you combine the unfortunate fact that Lowell suffered from
hypertension - which shows up clearly in the vessels of the eyeballs - with his
will to believe, it's no surprise that he pegged Venus as well as Mars with
teeming with intelligent, technologically capable inhabitants.