In 1931, Auguste Piccard went up in a balloon to an altitude of 15781 m, not far above the cruising altitude of an airliner. At the altitude, Earth’s curvature is still very slight and difficult to see, especially through the small portholes in his chamber.
In a Popular Science interview, Piccard was reported to have said that Earth “seemed a flat disc with an upturned edge.” Flat-Earthers quickly interpreted his statement as if he was telling us Earth is flat. In reality, in another interview, it is clear that he is convinced that Earth is a sphere. In his writings about his expeditions, the word “globe” was also mentioned several times.
Picard reached the altitude of 15781 m (51775 ft) before the Pop-Sci interview, not that far above the altitude of a commercial passenger flight today. Earth’s curvature is still not easy to ascertain from the altitude.
In the interview with RTS Radio, he said he did not notice Earth’s curvature from the small porthole of his chamber but was convinced that it would be possible to see the curvature if he were using a ruler. In his balloon flight, he was inside the chamber the entire time. He can only see the outside from several small portholes, 8 cm (3 in) in diameter.
He wrote his experiences in his book “Earth, Sky, and Sea.” He never once mentioned flat-Earth. On the contrary, the word ‘globe’ was mentioned many times.
His grandson claimed on his website that Auguste Piccard was the first man to witness the curvature of the Earth.
Table of Contents
The Popular Science Article
This is the curvature of the Earth should look like at the altitude of Auguste Piccard’s first flight.
RTS Radio Interview
This is the aforementioned RTS Radio interview. It was in French. Turn on subtitle and translation to get subtitles in English or another language. The relevant parts start from 7m25s.