26 AND COUNTING / The Liebenberg Chronicles / Eclipse 1
CLEMSON, South Carolina – Clemson University scientist Donald Liebenberg has personally witnessed and researched 26 total solar eclipses over the past 60-plus years.
Liebenberg, who has been an adjunct professor in the College of Science’s department of physics and astronomy since 1996, has literally travelled all over the world to enter the path of totality of solar eclipses. He has studied them from the ground, on ships in the middle of oceans, and in airplanes. He even watched one eclipse from the cabin of a Concorde supersonic airliner, where he was able to remain within the window of totality for an astounding 74 minutes.
Liebenberg’s first eclipse, chronicled below, was June 30, 1954 in Mellen, Wisconsin. His last one was March 9, 2016 aboard the cruise ship MS Vollendam off the coast of Indonesia.
All told, Liebenberg has spent more than two and a half hours in totality, which surpasses anyone else on Earth.
The upcoming Aug. 21, 2017 event over Clemson will mark Liebenberg’s 27th eclipse. He has also witnessed several other eclipses that were nearly – but not quite – in the path of totality.
Starting today, we will post a weekly chronicle of all 26 of Liebenberg’s eclipse adventures on our Eclipse Over Clemson blog. A few of these were less noteworthy than others – mainly due to weather conditions – so some segments will mention several eclipses, while others, such as this first one, will focus on just one eclipse.
Please sit back and enjoy this amazing adventure. It will be eye-opening, to say the least.
THE START OF SOMETHING BIG
Eclipse No. 1: June 30, 1954 Totality: 1 minute, 10 seconds
Where: Mellen, Wisconsin Weather conditions: Clear skies
By Dr. Donald Liebenberg
As a physics major at the University of Wisconsin in the early 1950s, I took an astronomy course from Dr. Arthur Code, who would later become a National Academy of Science member. My interest turned to the sun.
U.W.’s Washburn Observatory was also called Watson Solar Observatory, in honor of Dr. James Watson perhaps the most famous American astronomer of the latter half of the 19th century. Watson had found many planetoids and claimed he had seen a planet located closer to the sun than Mercury that he had named Vulcan. Watson came to U.W. from the University of Michigan in 1878 to establish the newly funded Washburn Observatory. He, of course, was not successful in finding Vulcan; but overall, his numerous other achievements remain legendary.
As part of my earliest research projects, I began to use a small portable telescope to draw positions of sunspots on paper from the observatory’s telescope images. I would walk up Observatory Hill near noon to make these observations.
Meanwhile, I was reading about the sun in the observatory’s library and found an article by (if I remember correctly) Curtiss and Wright, who had used a Fabry-Perot interferometer – a spectrum analyzer to disperse the colors of the rainbow – to observe two solar eclipses around 1920. They were attempting a high-resolution measurement of the then-well-known coronal emission green line at 530.28 nm, but were unsuccessful. The green line was finally identified in the late 1930s by Swedish professor Bengt Edle’n. By 1952, it was a corroborated fact that the corona was composed of a very hot plasma.
Professor Julian Mack, who was in the physics department at U.W. during my time there, was well-known for his use of Fabry-Perot interferometers (FPIs). I was doing a senior thesis under Mack and discussed my belief that an FPI could be used to study a solar eclipse that would occur on June 30, 1954, in northern Wisconsin. Mack and his associate, Dr. Joseph Hirschberg, took an interest, and we began to plan an expedition to Mellen, Wisconsin, for the eclipse. We took the pressure-scanned FPI, photoelectric detector equipment and a slate laboratory table top to be mounted on saw horses, but we still needed a sun tracker or heliostat. I asked Professor Code, who had graduated from the University of Chicago, and he suggested that U.C.’s Yerkes Observatory might have a heliostat. So we borrowed this clock-driven mirror unit, although no one at Yerkes could provide advice on how to set it up, which led to a problem on eclipse day when we finally decided to improve the setup. Professor Hirschberg rented a trailer for his station wagon and the three of us (including Julian Mack’s son, Newell) set out for Mellen after my graduation.
In Mellen, we found a hill with a good eastern view, since the eclipse would be in progress at sunrise and totality would occur with the sun at a low altitude. To move the equipment up the 50-foot hill, we borrowed a mortuary dolly that was especially useful to move the slate tabletop. We set up a tent, along with saw horses, tabletop, a pressure-scanned FPI with a photoelectric cell to capture the green line, and a strip chart recorder to give us a record. A mercury low-pressure lamp was used to tune and calibrate the FPI. Two small boys showed up to see what we were doing, and we hired them to keep the black flies – in season in June – off our backs.
A bright and clear morning sky greeted us on eclipse day. With the partial phase of the eclipse in progress at sunrise, the adjustment of the heliostat was more challenging – and as totality began, a green line was seen through the FPI. But the line profile was not recorded because the image from the heliostat went off the narrow slit of the pre-dispersion spectrograph. I had a brief look at the corona – what a spectacular sight! – but most of my time was spent working with the guiding mirror.
Despite the technical glitches, my first eclipse was a fascinating experience. But though I didn’t know it at the time, the best was yet to come.
Up next: Eclipse 2, May 8