Helium is a well-known element. Its name directly connects to the Sun, a celestial body far from Earth. This unusual origin story began with observations of our star.
Observing the Sun’s Spectrum
The first hint of helium’s existence came during a total solar eclipse on August 18, 1868. French astronomer Pierre Janssen, observing from Guntur, India, used a spectroscope to analyze the light from the Sun’s chromosphere. A spectroscope separates light into its component colors, revealing distinct lines that act as fingerprints for different chemical elements. Janssen noticed a bright yellow line with a wavelength of 587.49 nanometers that did not correspond to any element known on Earth at the time.
Just two months later, English astronomer Norman Lockyer independently observed the same yellow spectral line in the solar spectrum from London. Lockyer concluded that this unique spectral signature indicated the presence of an unknown element in the Sun’s atmosphere. This marked the first instance where an element was identified in a celestial body before its discovery on Earth.
The Proposed Name
Based on these groundbreaking solar observations, Norman Lockyer, along with English chemist Edward Frankland, proposed a name for this newly detected element. They chose “helium,” a name rooted in Greek mythology. The term comes from “helios,” the ancient Greek word for the Sun, which also refers to the Greek god personifying the Sun.
The “-ium” ending was appended to “helios” to align with the naming conventions for many metallic elements known at that time, such as sodium and magnesium. This choice reflected the scientific practice of categorizing new elements, even though it was initially unclear if helium would behave like a metal. Despite the compelling evidence, the idea of an element existing solely in the Sun was met with some skepticism in the scientific community.
Finding Helium on Earth
The existence of helium as a terrestrial element was confirmed nearly three decades later, resolving earlier doubts. In 1895, Scottish chemist Sir William Ramsay successfully isolated helium on Earth. Ramsay was actually searching for argon, but noticed the familiar bright yellow spectral line that matched the one observed in the Sun. This terrestrial discovery validated the prior solar observations and the name that Lockyer and Frankland had proposed. The finding of helium on Earth underscored its universal presence.