An eclipse of the sun occurs when the moon passes between the sun and the earth so that the sun’s light is fully or partially blocked. A total solar eclipse is rare and spectacular and not a little scary. The sun seems to disappear in the middle of the day and the sky darkens in a matter of minutes. The birds stop singing. People gather to watch through small pieces of smoky glass. They mutter to each other not to look directly at the sun, not to go blind. In the spring of 1900, the Smithsonian’s Astrophysical Observatory, then based in Washington, D.C., loaded several railroad cars with scientific equipment and headed to Wadesboro, North Carolina. Scientists had determined that this small Appalachian town would be the best location in North America for viewing an expected total solar eclipse on the 28th of May. In addition to the Smithsonian, teams from all over the world set up elaborate, massive telescopes. In the 1890s two other eclipse expeditions had preceded this one. And in both cases scientists had been thwarted in their attempts to witness the sight. In Lapland in 1896 scientists who had waited for weeks for the August 9th eclipse instead encountered a cloudy day; the expeditions to India in January 1898 were threatened by plague. In the words of the British Astronomical Association journal, "The course of Total Eclipse Expeditions, like that of true love, never runs smooth." Besides telescopes, each expedition brought with them an enormous amount of camera equipment. The Smithsonian Solar Eclipse Expedition hoped in particular to capture photographic proof of the solar corona. The Smithsonian’s photographer, Thomas Smillie, rigged cameras to seven telescopes and successfully made eight glass-plate negatives, ranging in size from eleven by fourteen inches to thirty by thirty inches. At the time, Smillie’s work was considered an amazing photographic and scientific achievement. Nearly a hundred years later, another Smithsonian photographer, Carl Hansen, joined an expedition to photograph a total eclipse in Panama. To nineteenth-century scientists, seeing was the most reliable of the senses, and photography, as a servant of sight, seemed capable of equal reliability. As Steve Turner, Smithsonian curator of physical sciences writes in his click! photography changes everything entry, the subject of many early scientific studies was the spectrum of light itself, the medium that made photography possible. The urge to measure the earth and sky with photographs is evident throughout early pictures. Dominque Francois Arago, the scientist who presented Louis Daguerre’s photographic invention to the French Chamber of Deputies in July of 1839, imagined that photography's greatest contribution might be as an aid to astronomers in their endeavors to map the heavens. These kinds of evidentiary pictures measure not only space, but also time. It is hard to wrap your mind around a photograph of a heavenly body made of light that has traveled for years to register in the earthly moment of the camera. More recently, studying images sent from x-ray telescopes mounted on satellites orbiting the sun, scientists have found that the dim areas at the edges of the corona’s active regions may hold the key to understanding how the sun converts vast amounts of energy from its surface into the solar wind. Understanding the origin of solar wind will improve our forecast of space weather and help astrophysicists understand the nature of stellar wind blowing from the surfaces of many other stars. Like the earliest photographic images, they also produce images of astonishing beauty.

Merry Foresta is the Former Director of the Smithsonian Photography Initiative.