Solar Rotation Determined from Thomas Harriot's Sunspot Observations of 1611 to 1613

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Science  08 Dec 1978:
Vol. 202, Issue 4372, pp. 1079-1081
DOI: 10.1126/science.202.4372.1079


In 1612 the sun's mean sidereal rotation rate was only 13.3° per day based on a series of 199 unpublished drawings by Harriot. By comparison with the rates in 1625 to 1626 and 1642 to 1644 it appears that the solar rotation was accelerating significantly in the cycles leading up to the Maunder minimum.