Harriot's Drawings and Observations

Drawings of the Moon

Harriot's drawings of the Moon
Moon drawing by Thomas Harriot.

Compare this with Galileo's Moon drawings. The preponderance in Harriot's notebook of drawings of the Moon made at first and third quarter suggests that he was attempting to establish the distance to the Sun using the method of Aristarchus.

First sunspot observations

Entries from the notebooks of Thomas Harriot
Entries from the notebooks of Thomas Harriot, dated 8 December1610.

Entries from the notebooks of Thomas Harriot, dated 8 December 1610. This is the earliest know pictorial record of sunspots. Harriot left nearly 200 drawings of sunspots from the period 1610–1612.Reproduced from the paper by W.M. Mitchell cited below.The text for December 8 reads:

"December 8 mane ho. That altitude of the sonne being 7 or 8 degrees. It being a frost & a mist. I saw the sonne in this manner. Instrument 10/1 B. I saw it twise of thrise. Once with the right eye & other time with the left. In the space of a minutes time. After the sonne was too cleare."

Interestingly, the text does not mention the spots explicitly, even though they are clearly indicated on the drawing. Like the Fabricius father and son team but unlike Galileo and Scheiner, Harriot observed the sun directly through his telescope. His observations were consequently limited to the hour following sunrise, when, as seen from Harriot's residence in Syon, the Sun was greatly dimmed by mist and fog over the river Thames.

Bibliography:
Bloom, T.F. 1978, Journal for the History of Astronomy, 9,177-122.
Mitchell, W.M. 1916, The History of the discovery of thesolar spot, Popular Astronomy, 22-ff.
Shirley, J.W. 1982, Thomas Harriot: a biography,Oxford: Oxford University Press.