The longest total solar eclipse ever seen

The longest total solar eclipse ever seen


Total eclipse of the Sun as seen from the luxury ocean liner “Canberra” floating in the Atlantic off the west coast of Africa near Mauritania on June 30, 1973. While ground observers were able to see totality for a little over 7 minutes at most, those on board the Concorde were able to see it for over 70 minutes!

Total eclipse of the Sun as seen from the luxury cruise ship “Canberra” floating in the Atlantic off the west coast of Africa near Mauritania on June 30, 1973. While ground observers could see the totality of the Sun for a maximum of just over 7 minutes, those on board the Concorde were able to see the eclipse for over 70 minutes! | Photo Credit: The Hindu Archives

Do you know who an umbraphile is? Literally meaning shadow lover, this term is used to describe a person who loves eclipses. Umbraphiles often travel to see these eclipses, even planning years in advance to be in the right place at the right time. They are also called eclipse chasers, a term that pretty well reflects what they actually do during eclipses.

It is normal for some people in astronomy to chase eclipses. The larger the duration of the eclipse, the better it is for them as it will give them more opportunity to learn about the phenomenon and what happens during the eclipse.

A total solar eclipse occurred on June 30, 1973, with the path of totality passing across much of Africa. Although it was already long, as ground observers could only get a maximum of 7 minutes and 4 seconds of totality, astronomers were always trying to extend it even further, if possible.

Idea

In 1972, astronomer Pierre Lina of the Paris Observatory came up with an idea—why not use the supersonic Concorde to fly across the Earth during a solar eclipse? (British astronomer John Beckman had independently arrived at the same idea but was unable to get the necessary permission.) Lina told French test pilot Andre Turcat his idea over lunch at a restaurant inside Toulouse Airport.

Impressed by what he had heard, Turket took the idea to his boss at Aerospatiale. Although it was tentatively approved and they agreed to cover the cost of the mission, it wasn’t until February 1973 that he received his final approval.

Planning Phase

Just four months before the eclipse, researchers and aviation staff went into overdrive. While those involved in the flight testing began customizing Concorde for the purpose and plotting the flight path, researchers planned the tests they could perform, keeping in mind the limitations of experimenting inside a high-speed aircraft.

There were a total of seven astronauts on board from France, Britain and the US, including Lena and Beckman (yes, they got a spot on board too!). There were also five others on board Concorde – a flight mechanic, two radio navigators and Turcat, who was flying the craft with the second pilot.

flight

On June 30, 1973, Concorde 001 took off from Las Palmas, Gran Canaria, in the Spanish Canary Islands, in search of a solar eclipse. On that day, the path of totality was about 250km wide and the moon's shadow was moving at a speed of 2,400km/h.

Despite all the test flights, there was a tense atmosphere on board the plane as Concorde intercepted the shadow of the moon over northwest Africa. The entire crew was anxiously waiting for the landing to be complete, which Concorde soon accomplished – a success thanks to all the precise planning and engineering.

After darkness fell, Turcat kept Concorde on course while astronomers used specially constructed pits on the roof to observe the event and carry out their experiments. Concorde reached a little over Mach 2 (twice the speed of sound, over 2,400 km/h) at one point and then flew at 2,200 km/h on the way to perfection.

Landing and closing

Flying in the direction of the moon's shadow, they stayed with it for as long as possible. But with the landing site in Chad fast approaching, the researchers quickly completed their experiments, and then headed out to take some glimpses themselves.

In total, this overall exercise was able to extend the duration of perfection for those on board the aircraft by 74 minutes! Having obtained more than 10 times the time obtained by the ground observer, the experimenters were able to study the Sun's corona, its chromosphere, and the intensity of sunlight passing through the top of the Earth's atmosphere (they were flying at an altitude of 17,000 meters for most of the flight).

The collaboration between different disciplines provided an important example of how experts from different fields can bring together their vast knowledge to push the boundaries of human knowledge. Although this was not the last eclipse viewing flight (not even for Concorde), it is certainly the longest solar eclipse viewing flight.


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