Blinded by the sight

¡SkyCaramba! Weekly astronomy blog for the week ending March 22, 2014

The most convincing beliefs we have are those we convince ourselves of. Even when confronted with evidence that what we hold true is false, we are not quick to abandon the conclusions we ourselves drew. The things Percival Lowell was most famous for are examples.

Around 1893, Lowell heard about Giovanni Schiaparelli’s purported observations of waterways on Mars in 1877. In Italian, Schiaparelli called them canali, which would be accurately translated channels. But canali looks like the word canal, and writers frequently mistranslated it. How much more exciting it was to think artificial canals (like the Suez Canal) instead of natural channels (like the English Channel) crossed Mars.

Lowell built an observatory to study Mars in time for its next close approach in 1894. To his delight, he saw canals too. Over the next 22 years, he published three books and gave many speeches about them. He also observed greenish areas of the red planet’s surface to change in brightness and the planet’s polar ice caps to grow and shrink.

The enthusiast concluded Martian beings depended on an extensive artificial irrigation system to grow crops. He also concluded water on Mars is so sparse, the Martians must have a very hard existence and may soon become extinct. The trouble with Lowell’s, Schiaparelli’s, and other astronomers’ observations was that not everyone saw the canals—even when they had bigger telescopes and clearer images. Furthermore, nobody could photograph them.

Lowell also pointed his telescope at Venus. Because it’s so bright, Venus can be seen in the daytime if one knows exactly where to look. Lowell did. To make the planet and the bright daytime sky not so painfully bright in his 24-inch scope, he put on a cover with a 3-inch hole in it. Then he observed Venus to also be criss-crossed with lines! He described them as having a hub and spoke arrangement. As with Mars, most other people didn’t see such features on Venus. Nor could they be photographed.

Today, we know the features on Mars don’t look anything like the things Lowell and others observed. And he couldn’t have seen any canals on Venus through the planet’s always cloudy atmosphere. Most likely, he saw the blood vessels in his own eye! You may see your own momentarily when you face a bright light or when a doctor shines a light in your pupil. The narrow beam of light coming through Lowell’s eyepiece could have caused the same effect.

The arrangement of blood vessels in any eye is unique. And except for people who have certain diseases that affect the eye, it doesn’t change. That would explain why Lowell’s Venutian spoke drawings always looked the same and the few other people who saw them drew them differently. Rather than suspect he was wrong, Lowell concluded Venus had such peculiar rotation as to always have the same side facing Earth. Apparently, Lowell didn’t take turns with each eye looking in the scope. We can only wonder how imaginatively he would have explained seeing a different canal system with each eye.

But let’s not dismiss Lowell’s significance in astronomy. His enthusiasm led many others to it as a hobby and a profession. We know so much more about other planets now than our ancestors then because Lowell made so many people want to know. And so, more people set about to develop better telescopes, devise new ways of taking scientific readings from a distance, and design spacecraft to travel to other worlds to take the close up looks we can’t yet.