22 February

02 FEB. 2005 Datum objave 798 Ogledi

1824: On 22 February 1824, Pierre Jules-César Janssen was born.

Janssen was a French astronomer who in 1868 devised a method for observing solar prominences without an eclipse.

Janssen observed the total solar eclipse in India. Using a spectroscope, he proved that the solar prominences are gaseous, and identified the chromosphere as a gaseous envelope of the Sun. He noted an unknown yellow spectral line in the Sun in 1868, and told Lockyer (who subsequently recognised it as a new element he named helium, from Greek "helios" for sun).

Janssen was the first to note the granular appearance of the Sun, regularly photographed it, and published a substantial solar atlas with 6000 photographs.


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