Walter Grotrian

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Walter Robert Wilhelm Grotrian (April 21, 1890 in Aachen; † March 3, 1954 in Potsdam) was a German astronomer and astrophysicist.

He discovered zodiacal dust (the cause of zodiacal light) in 1934 by studying the spectrum of the solar corona. The dust is an extension of the solar corona beyond Earth's orbit that reflects sunlight, which produces a faint illumination (zodiacal light) that can sometimes be seen shortly before sunrise or soon after sunset.

Grotrian studied the emission line from the solar corona in the green region of the spectrum; this emission line could not be attributed to any known chemical element and was thought to be a new element (which scientists named "coronium"). Grotrian and Bengt Edlén from Sweden demonstrated that the two observed emission lines arise from iron atoms that have lost about half their 26 electrons.[1]

[edit] Named after Grotrian

• Grotrian crater on the Moon
• Grotrian diagram
• Character in "Time Keeps on Slippin'" episode of Futurama