Astronomer Discovers Helium During Solar Eclipse

Summary

In the mid-19th century, astronomers sought new ways to study the Sun's atmosphere beyond the brief moments of total solar eclipses. French scientist Pierre Janssen traveled to Guntur in British India to observe the eclipse of August 18, 1868. Using a spectroscope, he examined the bright lines in the solar prominences and chromosphere, confirming their gaseous nature. Among the spectral lines was a prominent yellow one at approximately 587.49 nanometers, distinct from known elements like sodium. Janssen quickly realized this indicated a previously unknown element. Independently, English astronomer Joseph Norman Lockyer made similar observations shortly afterward, leading to the naming of helium after the Greek word for the Sun.

Why It Matters

The discovery provided the first evidence of an element not yet found on Earth and advanced solar spectroscopy techniques still used today. Helium later proved essential in applications from balloons and cryogenics to modern medical imaging and space exploration. It exemplified how eclipse observations drove fundamental advances in chemistry and astrophysics.

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Daily Earth View: Astronomer Discovers Helium During Solar Eclipse connects to space, astronomy, satellites, or Earth observation history.

Sources

1. Pierre Janssen, Wikipedia. Accessed 2026-07-02.
2. Discovery of helium, Encyclopædia Britannica. Accessed 2026-07-02.