Pierre Janssen, who was an astronomer, discovered helium on August 18, 1868. Wait, you ask, what is an astronomer doing discovering a chemical element? Ah, that’s the right question. Not only did Janssen discover helium, he was the first person in history to discover a new element, but not on Earth. In fact, at the time, nobody knew whether there was any helium on Earth. Janssen discovered it 93 million miles away.
That distance is a clue — helium was discovered on the Sun before it was found on Earth. Janssen travelled to India to observe the solar eclipse on the date of his discovery. He wanted to observe the atmosphere of the sun — the chromosphere — with a spectroscope.
A spectroscope is a fairly simple device; it just separates light into its inherent spectrum, like a prism would. In fact, the first spectroscopes were nothing more than prisms. But by 1868 they used mirrors and an etched grating, and displayed a more detailed spectrum. They’re still simple, though; you could make one yourself without any special equipment — the main things you need are a cardboard box and some kind of reflective surface, like aluminum foil. You might have made one already — think back to that science fair project when you were in about 6th grade?
The spectrum of a beam of light can tell you a number of things about it. If you’re observing original light — that is, from the source, not from a reflection — the spectrum will be brighter and darker in different areas. Where the colors are brighter, it indicates something is producing that particular wavelength of light — a particular chemical process, in the case of a flame, or the presence of a given element in the case of a nuclear source like a star. Each element glows at its own wavelength, given a consistent temperature.
With a diffraction spectroscope, the lines of colors are separated by dark lines that indicate another element is absorbing that part of the spectrum. They’re called Fraunhofer lines after Joseph von Fraunhofer, who invented the modern spectroscope in the early 1800s.
Anyway, when Janssen saw the spectrogram of the Sun’s corona, he couldn’t help but notice a very bright yellow line. It was already well known that the pattern of lines in a spectrogram was a kind of “fingerprint” indicating the presence or absence of elements — and that yellow line was something completely new. He didn’t know what it was yet, but he made careful notes.
The yellow line was so prominent that Janssen made a second discovery that day — he realized that it would be possible to measure the chromosphere without waiting for an eclipse. The yellow line was so bright, he thought it would show up regardless. When the eclipse ended, he set up his equipment to try it — and it worked.
Janssen published his results, and others set about replicating the observation. Joseph Lockyer set up a new, better spectroscope a couple of months later in England, and saw the same yellow line. He consulted with Edward Frankland, a chemist, and when they established that it wasn’t some different type of hydrogen, decided it must be a new element. They were the ones who named it “helium”, after the Greek word “helios”, which means sun.
Janssen wasn’t finished, though. he went on to invent the “Photographic Revolver” — the first device able to make a series of photos showing movement. Then in 1893 he had an observatory built at the top of Mont Blanc in order to make observations with less atmosphere in the way. He didn’t build the observatory, but at age 69 he climbed the mountain in order to use it. He spent a week at 15,000 feet using his observatory.
Janssen is primarily known for his discovery of helium. Karl Jatho didn’t need any helium in 1903; he just used the flying machine he’d invented to make a powered flight — several months before the Wright Brothers did. At least, he might have. Jatho’s airplane design seems to lack any control surfaces, but it might not have mattered, since his first flight was only about the length of a football field, the same distance as the Wright Brothers’ first attempt.
People were, reportedly, there to see Jatho’s initial flights, and they gave a notarized statement to that effect. That would have sealed the deal and made Jatho the inventor of powered flight — except they didn’t make their statement until 30 years later.
In the 1930s, Jatho’s original assistant built a replica of the original flyer to show that at least it COULD have worked, but bad weather delayed his attempt, and he never managed to reschedule it for some reason.
Then in 2006, another replica was made. Once again bad weather delayed the test, after which the owner of the replica — the Hannover Airport — wouldn’t let anybody try it because they wanted to use it as an exhibit.
The Janssen Photographic Revolver could have settled things once and for all, but there aren’t any photos of Jatho’s original flights. He went on to build more airplanes, and even founded an aircraft factory, but whether he was really the first to fly is still…well…up in the air. Just like helium.
