Galileo made a series of sunspot drawings in the summer of 1612. The drawings are particularly illustrative when viewed in sequence because they were made at approximately the same time of day. The 36 drawings illustrate the motion of sunspots across the disk—which is actually a sequence showing the rotation of the Sun. The changes in the sunspot groups and sizes can also be observed.
The equator and rotation axis of the Sun can be determined after watching the direction of the sunspots over time. The images are taken from Professor Owen Gingerich's copy of the first edition of Galileo's Istoria e Dimostrazioni Intorno alle Macchie Solari e Loro Accidenti (History and Demonstrations Concerning Sunspots and Their Properties), published in 1613.
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Learn more about Sunspots
on the Exploratorium's Sunspot Web site.(Requires
an Internet connection) |
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