John A. Eddy, Date of Birth, Place of Birth, Date of Death
TweetJohn A. Eddy
American astronomer
Date of Birth: 25-Mar-1931
Place of Birth: Pawnee City, Nebraska, United States
Date of Death: 10-Jun-2009
Profession: astronomer
Nationality: United States
Zodiac Sign: Aries 
About John A. Eddy
- John Allen "Jack" Eddy (March 25, 1931 – June 10, 2009) was an American astronomer who published professionally under the name John A.
- Eddy but much of the content referencing him can be found under his nickname Jack which he preferred to use.
- In 1976 Dr.
- Eddy published a landmark paper in Science titled "The Maunder Minimum" where, using the Nineteenth Century works of Edward W.
- Maunder and Gustav Spörer, he identified a 70-year period from 1645 to 1715 as a time when solar activity all but stopped.
- In making the case for the anomaly, he gathered and interpreted data from a wide variety of sources, including first-hand accounts from extant historical observations of the Sun going back to the telescopic observations of Galileo and other contemporary scientists of the 17th and early 18th centuries; from historical reports of the aurora borealis observed in past centuries in Europe and the New World; from visual observations of sunspots seen with the unaided eye at sunrise and sunset in dynastic records from the Orient; from existing descriptions of the eclipsed Sun; and from measurements of carbon-14 in dated tree-rings.
- In the last of these, which can be used as a proxy indicator of solar activity, he found evidence of other similar periods of solar quiescence in the distant past, the most recent an even longer 90-year span, from about 1460 until 1550, which he named the Spörer Minimum.
- Both the Maunder and Spörer minima fell during the coldest parts of the Little Ice Age, which suggested a meaningful connection between the longer term behavior of the Sun and of the Earth's mean surface temperature.
- In advancing the theory that the Sun is a variable star Eddy observed: "It has long been thought that the Sun is a constant star of regular and repeatable behavior.
- Measurements of the radiative output, or solar constant, seem to justify the first assumption, and the record of periodicity in sunspot numbers is taken as evidence of the second.
- Both records, however, sample only the most recent history of the Sun."
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