Earlier this evening, I blogged about Cartography and the Moon, 1647 and Johannes Hevelius (1611-1687). While doing the research, I came across this image of Hevelius’ earliest drawing of sunspots. Since it wasn’t “Moon” related, my son, Jason ( check out his blog, “Jason’s Blog- Work in Progress”), said I should post it as a bonus feature. So, here it is!
So, what is the “Maunder Minimum“? ” The number of sunspots observed on the solar surface varies fairly regularly, with an average period of 11-years. However, if we look at the variation of the sunspot number with time, we find that for a period of about 70 years, from A.D. 1645 to 1715, practically no sunspots have been observed. In other words, during this time the solar cycle has been interrupted. This period of time is called the Maunder Minimum.“
Did You Know?
In 1679 the English astronomer Edmond Halley visited Hevelius and compared the use of a sextant having telescopic sights with Hevelius’ sextant with open sights. Hevelius showed that he could determine stellar positions about as accurately without a telescope as Halley could with one.
Editor’s Note: Featured image The Photosphere and Sun-spots is by S.P. Lngley | The Photosphere and Sun-spots | Popular Science Monthly, vol. 5 (September 1874)