Which astronomer first noted clear observational discrepancies suggesting missing mass while studying the Coma Cluster?

Answer

Fritz Zwicky

In the 1930s, Fritz Zwicky studied the Coma Cluster and proposed the existence of "dunkle Materie" because the galaxies moved too fast to be held together only by visible mass.

Which astronomer first noted clear observational discrepancies suggesting missing mass while studying the Coma Cluster?
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