In the summer of 1973, a small team of scientists boarded the supersonic jet Concorde 001 not to break aviation records, but to follow a solar eclipse. On 30 June, above the Sahara Desert, they achieved what no one had before: 74 minutes of uninterrupted totality.
From the ground, the longest possible total eclipse lasts a little over seven minutes. That day’s eclipse promised unusually long duration, but even then the natural limit could not be surpassed without leaving Earth’s surface. Concorde changed that.
Converting Concorde into a flying observatory
Concorde 001, the prototype supersonic jet, was modified for the mission. Engineers cut observation portholes into its roof and installed scientific equipment, turning the passenger plane into a high-altitude laboratory.
It took off from Las Palmas in the Canary Islands and climbed to 55,000 feet. Flying at Mach 2.05, more than 2,500 kilometres an hour, it intercepted the Moon’s shadow, which was racing across Earth at 2,400 kilometres an hour. By keeping pace, the aircraft stayed within the umbra far longer than stationary observers.
The jet crossed Mauritania, Mali, Niger and Nigeria before landing in Chad. Aboard were researchers from Los Alamos National Laboratory, the Paris Observatory, the Kitt Peak National Observatory, Queen Mary University of London, the University of Aberdeen, and France’s National Centre for Scientific Research.
Precision against the clock
The flight’s success depended on exact timing. A scientific paper on the mission later noted: “Had the aircraft been 2 min early on arrival in the eclipse path, the period of totality would have been reduced by 25 min and one natural contact would have been lost.”
These “contacts” mark the phases when the Moon first touches the Sun’s disc and when it departs. Scientists on the Concorde were able to observe a seven-minute first contact and a 12-minute third contact, much longer than anyone on the ground could experience.
At over 16,000 metres, the aircraft avoided cloud and turbulence, securing clear skies. But even at such altitude, aligning precisely with the shadow was a demanding feat of both piloting and astronomy.
Unlocking the solar corona
The aim was to study the solar corona, the Sun’s outer atmosphere. Despite appearing faint, the corona is hundreds of times hotter than the solar surface, a puzzle that still challenges physicists today.
Five scientific teams carried equipment to examine its structure, record dynamic features and capture high-resolution images. The extra time in totality provided data that ground-based telescopes could never gather.
Donald Liebenberg, a physicist from Los Alamos who joined the flight, later wrote: “We intercepted the totality and stayed within it for 74 minutes before descending and landing in the African nation of Chad. At 74 minutes, our group aboard the Concorde set a record for the amount of time spent in totality that has never been broken. It was an experience I will never forget.”
He later added in a separate reflection: “To say the least, it was an experience I will never forget.” By then, he had logged more eclipse time than any other human.
The experiment that changed eclipse science
The researchers concluded at the time that supersonic flight had set a new benchmark, noting, “future plans should favour this method over more conventional approaches.”
The Concorde experiment showed that speed and altitude could stretch nature’s limits. For the scientists, it opened a new paradigm in eclipse research, one where the skies could be pursued rather than endured.
Later, Concorde was even used for tourist eclipse flights. In August 1999, three Concordes carried paying passengers into the Moon’s shadow, though the experience was far shorter and complicated by the aircraft’s small windows. Those flights proved popular, but none came close to the feat of 1973.
From Concorde to satellites
Since Concorde’s retirement, scientists have looked for new ways to extend totality. In 2024, NASA used WB-57 jets to study an eclipse over North America. Bharat Kunduri, who led a project to study the ionosphere, explained: “The eclipse basically serves as a controlled experiment. It gives us an opportunity to understand how changes in solar radiation can impact the ionosphere, which can in turn impact some of these technologies like radar and GPS that we rely on in our daily lives.”
The European Space Agency is preparing Proba-3, a pair of satellites designed to create artificial eclipses in space by blocking the Sun’s light with precision alignment.
Yet, despite these advances, Concorde’s 74 minutes remain unbeaten.
Holding darkness a little longer
The 1973 mission bridged two eras: one of ingenuity with modified aircraft, and another now dominated by satellites and digital sensors. It proved that with the right mix of aviation and science, human beings could stretch natural boundaries.
By synchronising with the Moon’s shadow, Concorde 001 gave the world its longest look at a solar eclipse. Half a century later, the record still holds, and for many astronomers it remains the greatest eclipse chase ever attempted.
From the ground, the longest possible total eclipse lasts a little over seven minutes. That day’s eclipse promised unusually long duration, but even then the natural limit could not be surpassed without leaving Earth’s surface. Concorde changed that.
Converting Concorde into a flying observatory
Concorde 001, the prototype supersonic jet, was modified for the mission. Engineers cut observation portholes into its roof and installed scientific equipment, turning the passenger plane into a high-altitude laboratory.
It took off from Las Palmas in the Canary Islands and climbed to 55,000 feet. Flying at Mach 2.05, more than 2,500 kilometres an hour, it intercepted the Moon’s shadow, which was racing across Earth at 2,400 kilometres an hour. By keeping pace, the aircraft stayed within the umbra far longer than stationary observers.
The jet crossed Mauritania, Mali, Niger and Nigeria before landing in Chad. Aboard were researchers from Los Alamos National Laboratory, the Paris Observatory, the Kitt Peak National Observatory, Queen Mary University of London, the University of Aberdeen, and France’s National Centre for Scientific Research.
Precision against the clock
The flight’s success depended on exact timing. A scientific paper on the mission later noted: “Had the aircraft been 2 min early on arrival in the eclipse path, the period of totality would have been reduced by 25 min and one natural contact would have been lost.”
These “contacts” mark the phases when the Moon first touches the Sun’s disc and when it departs. Scientists on the Concorde were able to observe a seven-minute first contact and a 12-minute third contact, much longer than anyone on the ground could experience.
At over 16,000 metres, the aircraft avoided cloud and turbulence, securing clear skies. But even at such altitude, aligning precisely with the shadow was a demanding feat of both piloting and astronomy.
Unlocking the solar corona
The aim was to study the solar corona, the Sun’s outer atmosphere. Despite appearing faint, the corona is hundreds of times hotter than the solar surface, a puzzle that still challenges physicists today.
Five scientific teams carried equipment to examine its structure, record dynamic features and capture high-resolution images. The extra time in totality provided data that ground-based telescopes could never gather.
Donald Liebenberg, a physicist from Los Alamos who joined the flight, later wrote: “We intercepted the totality and stayed within it for 74 minutes before descending and landing in the African nation of Chad. At 74 minutes, our group aboard the Concorde set a record for the amount of time spent in totality that has never been broken. It was an experience I will never forget.”
He later added in a separate reflection: “To say the least, it was an experience I will never forget.” By then, he had logged more eclipse time than any other human.
The experiment that changed eclipse science
The researchers concluded at the time that supersonic flight had set a new benchmark, noting, “future plans should favour this method over more conventional approaches.”
The Concorde experiment showed that speed and altitude could stretch nature’s limits. For the scientists, it opened a new paradigm in eclipse research, one where the skies could be pursued rather than endured.
Later, Concorde was even used for tourist eclipse flights. In August 1999, three Concordes carried paying passengers into the Moon’s shadow, though the experience was far shorter and complicated by the aircraft’s small windows. Those flights proved popular, but none came close to the feat of 1973.
From Concorde to satellites
Since Concorde’s retirement, scientists have looked for new ways to extend totality. In 2024, NASA used WB-57 jets to study an eclipse over North America. Bharat Kunduri, who led a project to study the ionosphere, explained: “The eclipse basically serves as a controlled experiment. It gives us an opportunity to understand how changes in solar radiation can impact the ionosphere, which can in turn impact some of these technologies like radar and GPS that we rely on in our daily lives.”
The European Space Agency is preparing Proba-3, a pair of satellites designed to create artificial eclipses in space by blocking the Sun’s light with precision alignment.
Yet, despite these advances, Concorde’s 74 minutes remain unbeaten.
Holding darkness a little longer
The 1973 mission bridged two eras: one of ingenuity with modified aircraft, and another now dominated by satellites and digital sensors. It proved that with the right mix of aviation and science, human beings could stretch natural boundaries.
By synchronising with the Moon’s shadow, Concorde 001 gave the world its longest look at a solar eclipse. Half a century later, the record still holds, and for many astronomers it remains the greatest eclipse chase ever attempted.
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