Aiken and the Transit of Venus

When used in association with astronomy, a "transit" refers to the passage of a heavenly body across the meridian of a specific location or through the field of a telescope. The transit of Venus takes place when the planet travels directly between the Earth and the sun. When this phenomenon occurs, a tiny part of the sun is obscured and a small black disc appearing as a shadow is visible as it moves across the face of the sun. The Venus transit lasts approximately six hours and looks similar to a solar eclipse created by the moon. However, because the moon is much closer to Earth than Venus is, the moon’s eclipse appears much bigger to us even though Venus is almost four times larger than the moon.

Before the age of computers, scientists throughout history were especially interested in tracking and observing the transits of Venus. The calculations they gathered provided important information that helped them calculate the distance between the Earth and the sun. These transits occur every 243 years, with a pattern consisting of pairs of transits that are eight years apart and separated by lengthy, unequal gaps of years on either end. The most recent occurrence of the pair in the transit of Venus occurred on June 8, 2004. The final appearance of the latest pair will happen June 6, 2012.

From Germany to Aiken

Before 2004, the last pair of transits occurred in December of 1874 and then on December 6, 1882. This was a much-awaited event for scientists from around the world. Dr. Julius Franz, professor of astronomy and chief astronomer at the Royal Observatory in Koenigsburg, Germany, traveled to Aiken, South Carolina to see if the location would provide optimum conditions for the placement of his specially built telescope. This was to be the second of six stations situated at specific points around the world. Scientists selected Aiken because its climate provided one of the best chances of fair weather and, thus, a better chance for observing the transit from the second position station.

Financed by the German government, Dr. Franz and his student assistant arrived in Aiken six weeks before the transit. His massive equipment began to show up at the railway station shortly after he did. After searching for several days, Dr. Franz determined that the best site for the construction of the observatory was on the estate of Mr. Henry Smith. At that time, Smith’s property was far enough from town that the lights would not mar visibility and far enough from the railroad tracks so that no vibrations from a passing train would interfere with the sensitivity of the instruments. Any jarring of the ground could potentially compromise Dr. Franz’s calculations. Today, the area where the observatory was built is in the vicinity of Barnwell and Edgefield Avenues between Laurens and Newberry Streets.

The construction continued almost around the clock for six weeks. The structure of the observatory, including the housing for the sensitive instruments, was an iron heliometer tower. The term “heliometer” refers to instruments that were originally designed for measuring the sun’s diameter. In 1882, the use of the heliometer tower helped scientists take the measurements of two celestial bodies at such great distances from each other that they couldn’t both be included in the view of an ordinary telescope at the same time. The observatory was constructed in two sections, each about twelve feet in diameter. Each of the sections revolved independently of the other.

A Cloudy Evening

As the evening of the transit approached, so did the clouds. Books and articles about the success of the observation of the transit of Venus in Aiken in 1882 tell different versions of the story. One reports that a heavy rain fell from midnight to sunrise the next morning; other versions claim there were only heavy clouds. In any case, all accounts agree that the sun finally appeared around noon on December 6. Then, scientists were able to complete three sets of heliometer measurements and, although it was not without its challenges, the entire mission was considered a success. Dr. Franz was hailed as a hero and given a pension for life by Germany. In America, the composer and famous conductor John Phillip Sousa wrote a song titled “The Transit of Venus March.”

Remnants of the iron observatory were moved from their original spot and can now be seen on the grounds of the Aiken County Historical Museum. But a limestone slab still exists where the observatory was constructed, now the backyard of a private residence on Edgefield Street, with this inscription: “Venus Durchgang 1882 Deutsche Station II 5h 26m 52s 6 W 33° 33’ 51” N”