[Jason Krüger, CC BY-SA 4.0 , via Wikimedia Commons]

August 18, 1868: A Discovery That Could Leave You Breathless

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On August 18, 1868, one of the most abundant gases in the universe was discovered. Though less common on Earth, the discovery of helium marked a significant milestone in the history of chemistry and physics and has been credited to two scientists who made the revelation simultaneously, Pierre Janssen and Joseph Norman Lockyer.

That year, a solar eclipse had the world’s scientific communities excited. To view one of space’s great spectacles, Janssen traveled to Guntur, India, to observe the solar eclipse, writes The American Physical Society. “He focused on the solar prominences and concluded they mostly comprise hydrogen gas, heated to extremely high temperatures. But on August 18, when he observed the sun’s spectrum through his spectroscope, he noticed that the wavelength of the yellow line supposedly indicating the presence of sodium didn’t actually match up to the wavelength for that element. In fact, it didn’t match the wavelength of any known element to date. The line was bright enough, he thought, that it should be visible even without the aid of an eclipse, provided a means could be found to filter out all but that wavelength of visible light. That is how he came to invent the spectrohelioscope to better analyze the sun’s spectrum.

Some 5,000 miles away, on October 20, 1868, the English astronomer Joseph Norman Lockyer also succeeded in observing the solar prominences in broad daylight. His paper detailing those observations arrived at the French Academy of Sciences on the same day as Janssen’s paper, so both men received credit for the discovery of helium.

Initially it was a dubious honor: Many colleagues doubted this could be a new element and ridiculed their conclusions. Others thought helium could exist only in the sun. In 1882, the Italian physicist Luigi Palmieri was analyzing lava from Mount Vesuvius when he noticed that same telltale yellow spectral line in his data — the first indication of helium on Earth. It would be another 12 years before the Scottish chemist William Ramsey found further experimental evidence of this new element.”

Ramsay and his collaborators soon realized that helium was distinct from any other element they had encountered, as it remained a gas even at extremely low temperatures, making it the first noble gas to be discovered.

The discovery of helium had profound implications for various fields of science and technology. In the early 20th century, helium’s low boiling point and unique properties made it an invaluable resource for applications in cryogenics, particularly in the field of superconductivity research. The gas also enabled scientists to approach absolute zero temperatures and led to the discovery of superfluidity in helium-4 isotopes. Moreover, helium’s inert nature made it ideal for filling balloons and airships. The rarity of the gas combined with its uses led to the establishment of the U.S. Federal Helium Reserve in 1925 to ensure a strategic reserve of this precious gas.

Helium has also played a pivotal role in understanding the structure of matter. Its discovery and subsequent studies provided insights into atomic behavior and helped refine the understanding of the periodic table. As an element that defied common chemical reactions due to its inert nature, helium showcased the diversity of elements and their distinct characteristics. From its early identification in the Sun to its applications in various scientific and industrial contexts, the discovery of helium reshaped our understanding of the universe and continues to impact diverse fields of research and technology.

It also entertains children when you suck it in from a balloon and start talking at birthday parties. 

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