Early Astronomy in the University of Michigan Collections

De Tribus Cometis

Grassi’s treatise includes an engraved foldout with numerous drawings, tables, and diagrams, mostly recording the dates and locations in which the comets were observed from various European cities. For instance, on the upper left corner, we read that the first comet was seen in Rome on August 29, 1618, under the hind foot of the Ursa Maior, as it is shown by the letter L.

On Comets



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