26 AND COUNTING / The Liebenberg Chronicles / Eclipse 5
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 fifth eclipse, chronicled below, was May 30, 1965 in an airplane 40,000 feet above the South Pacific. 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.
Today is the fifth chronicle of all 26 of Liebenberg’s eclipse adventures on our Eclipse Over Clemson blog.
Please sit back and continue to enjoy this amazing adventure.
THE FIRST TIME IN FLIGHT
Eclipse No. 5: May 30, 1965 Totality: 4 minutes, 47 seconds
Where: Over the South Pacific Weather conditions: above the clouds
By Donald Liebenberg
After the interesting circumstances following the 1963 total solar eclipse in the Northwest Territories of Canada, we gained permission to observe the 1965 total solar eclipse aboard an NC-135 plane operated by the U.S. Air Force but commissioned to the Los Alamos National Laboratory (LANL) in support of the newly signed limited test ban treaty.
We set about designing equipment that would work effectively on an airplane. We decided to use two interferometers, one that was pressure-scanned and another that was not pressure-scanned so that it could be used with photographic plates. The equipment was attached to an aluminum table top along with a specially designed 10-inch diameter refractor lens. A tracking mirror directed light to the lens and through the instruments to maintain stability against the aircraft’s motion. While the overall design was not particularly aircraft friendly, the equipment performed well on our first test flight.
Dr. Art Cox and Don Eilers provided computations of the eclipse path and coordinates for the aircraft intercept. This was complicated, because the aircraft would be traveling about 500 mph while the eclipse would travel at about 1,400 mph, with the path of totality being about 100 miles wide. Accurate path and time calculations had to be translated by the aircraft navigators to a flight plan. Navigation in the middle of the Pacific Ocean without today’s modern GPS required extraordinary skill.
As it turned out, three laboratory planes elected to go to this eclipse. With Col. N. Garland as the Air Force leader, we departed Hawaii and headed for American Samoa. On eclipse day, we took off early to meet the totality near local noon, which would give us the longest duration of totality. As we got closer to second contact, high cirrus appeared above us, so Col. Garland used military thrust to lift us above the clouds. This put additional stress on the old, water-assisted takeoff engines on all our planes, but we were able to rise above the cirrus at more than 40,000 feet.
Totality overtook us and we began recording data. We ended up spending four minutes and 37 seconds in totality, which was extended by the aircraft’s speed along the path. After that, we flew back to Samoa. Col. Garland never did tell us how much fuel he had left in our plane, but clearly it was less than standard.
After landing in Hawaii, I flew home on a commercial airline. In the airport terminal, I was interviewed by a New York Times journalist about our flight, and an article appeared in newspaper’s next edition.
After I was home, my photographic plates were developed. These would be later analyzed with the help of University of Wyoming professor Robert Bessey and his graduate student, Bobby Watson. The three of us found that the temperature of the corona was in many places greater than 2 million degrees Kelvin (about 3.6 million Fahrenheit) and temperatures in the corona increased with distance from the solar surface.
At the time of our measurements, the coronal temperatures frequently measured from coronagraphs were about 1 million Kelvin and sometimes less, while our measurements taken during the 1965 eclipse were significantly higher. Our future eclipse measurements and data collected by space observatories would find temperatures reaching more than 10 million Kelvin.
Solar activity such as flares and ejections frequently begin on the sun’s surface and move into the corona. Coronographs are designed to block the bright solar surface so that the dimmer corona can be studied. However, they don’t capture data as close to the solar surface as is possible during a total eclipse. Because of this, one of the main reasons of interest in total eclipse studies is the chance to record evidence of the solar activity interacting with the corona closest to the surface. Our results showing the corona’s temperature increases from the surface helped modify theories about how energy flows through the corona and allows charged particles to escape from the sun as the solar wind.
Up next: Eclipse 6, June 5