Lately, a lot of people have been reminding me about the fallibility of science. Mostly, they are trying in an indirect way to question the strong scientific evidence that human activity has contributed to climate change.

They have a right to be skeptical of science. In a sense, science is partly responsible for the current mess. Advances in science and technology spurred the industrial revolution, and world temperatures have been rising ever since.

In fact, scientists have been wrong about the universe in the past. Stubbornly, most of them clung to the Earth-centered model of the solar system until the evidence for a sun-centered model was overwhelming.

Thanks to gigantic telescopes, humans think they know a lot about the universe these days. However, nothing is truly certain in astronomy and science in general. Understanding comes in small increments, slowly and arduously gained from painstaking research. Thus, every discovery about the universe is incorrect to some degree. We must take comfort in the assumption that each new assertion seems a lot less incorrect than the one before.

Here’s a case in point.

As late as 100 years ago, humans knew practically nothing about Earth’s nearest neighbor, our only natural satellite, the moon. Based on the best available evidence, even brightest astronomers made claims about the moon that seem in retrospect to be exceedingly weird.

If you don’t believe me, grab a small telescope and look at the crater Eratosthenes. (A detailed moon map will help you here.) Look first for the Apennines mountain range, a long, curved chain visible just north of the moon’s center. The Apennines act as the southeastern boundary of the large, dark, mostly empty splotch called Mare Imbrium, the “Sea of Rain.”

Punctuating the western end of the mountain chain is one of the moon’s most perfect craters. Exquisitely round with high terraced walls, Eratosthenes is small at only 38 miles wide. Its gorgeous central mountains look very much like a dimple in a small telescope. Here we see the imprint of the massive impact of some minor asteroid on an unsuspecting moon a long time ago.

Eratosthenes would be just another impact crater except for the work of William Pickering, the most respected lunar and planetary observer of the beginning of the twentieth century. Pickering worked at the prestigious Harvard College Observatory. Among his accomplishments were the discovery of Phoebe, Saturn’s most distant moon, a detailed set of lunar photographs, and careful, groundbreaking observations of Mars.

In 1919, Pickering took his telescopes to Jamaica, an island paradise where skies are often exceedingly clear. (Astronomy can be a tough job sometimes.) He paid particular — even obsessive ­ — attention to the rather minor crater in question. Night after night, he observed it and began to notice an odd pattern. Over the course of a monthly lunar cycle, a number of strange, dark patches seemed to move in a regular pattern over the crater’s floor.

Earlier, Pickering had persuaded himself on very tenuous evidence that the moon not only had an atmosphere but patches of vegetation. He had also studied the earthbound movements of the giant buffalo herds across the American west and the migrations of the fur-bearing seals of the Pribiloff islands.

He suggested that an astronomer on the moon would see the same kind of dark patches if he or she were watching those migrations on Earth. According to Pickering, the dark patches on the crater floor moved about twenty miles and completed their motion in twelve days. The movement, he argued in a 1924 paper, “involves an average speed of six feet a minute, which … implies small animals.”

Some sort of insect seemed to be the most likely solution. Those lunar moths, or whatever they were, traveled regularly between their breeding grounds and the large expanses of vegetation nearby.

Pickering’s reputation as a careful observer was so well established that other astronomers were forced to take his insect theory seriously, but in the end no one could replicate his observations. Despite the skepticism of his colleagues, Pickering held fast to his views until his death in 1938.

Of course, we now know with certainty that the moon has neither atmosphere nor liquid water to support even the simplest form of life. Apollo astronauts found no migrating moon moths. Sorry.

What was Pickering seeing on Luna? Nobody knows. One possibility arises from the word “lunatic.” The term refers to the old superstition that staring too long at the moon will cause you to become unhinged.

I doubt it, however. Astronomers mostly don’t credit direct visual observation of astronomical objects, and with good reason. The eye is an imperfect scientific instrument. It is subject to fatigue. It can be tricked. We have all experienced so-called optical illusions. Most importantly, our visual impressions are filtered through our preconceptions and expectations.

Thus, our general impression that, say, it’s been a cold winter does not justify skepticism about global warming. Scientists look at a lot of evidence and work very hard to look at a lot of evidence beyond our very limited personal experience.

We also let our emotional responses and personal needs color our conclusions. The long-term goal of slowing climate change and preventing disaster comes into direct conflict with our short-term economic needs. It’s hard to worry about your unborn grandchildren when your children are hungry now.

Still, we must take the long view and sacrifice in the short term to achieve long-term prosperity and safety.

Perhaps at the dawn of the 22nd century, people will look back 100 years and chuckle, as we chuckle now at Pickering, at the odd claims of those crazy astronomers and climatologists who live now. Or perhaps they will revere them as the saviors of our species. Only 100 years of tireless research and hard experience will tell the tale. But can we afford to take the chance?

Tom Burns


Tom Burns is director of the Perkins Observatory in Delaware.