Featured Image: Learning About the Sun from Historical Observations

sunspot observations

Example page of Selenographia with a sunspot drawing made by Hevelius in September 1643. [Carrasco et al. 2019; Selenographia, courtesy of the Library of the Astronomical Obs. of the Spanish Navy]

Click on the image above to see the full view of the observatory of Johannes Hevelius, a Polish astronomer who lived in the 1600s. This print is found in Hevelius’s book Selenographia and is reproduced courtesy of the Library of the Astronomical Observatory of the Spanish Navy in a recent solar activity research study led by Victor Carrasco (University of Extremadura, Spain and Southwest Research Institute). Hevelius used his observatory to chart daily observations of sunspots (note, in the above image, the projection of the Sun’s disk from the telescope coming through the left wall onto a vertical screen at the right). His records from 1642 to 1645 are the only systematic sunspot observations we have from just before the Maunder Minimum, a prolonged period of reduced solar activity between 1645 and 1715. Carrasco and collaborators have now reevaluated Hevelius’s observations, using them to explore the first hints of this quiet time for the Sun. For more information, check out the original article below.


“Sunspot Characteristics at the Onset of the Maunder Minimum Based on the Observations of Hevelius,” V. M. S. Carrasco et al 2019 ApJ 886 18. doi:10.3847/1538-4357/ab4ade