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#16a. Discovery of the Sunspot Cycle

Excerpts from Solar Observations During 1843 by Heinrich Schwabe, (Astronomische Nachrichten, vol. 20., no. 495, 1843)

The weather throughout this year was so extremely favorable that I have been able to observe the Sun clearly on 312 days; however, I counted only 34 groups of sunspots....

From my earlier observations, which I have reported every year in this journal, it appears that there is a certain periodicity in the appearance of sunspots and this theory seems more and more probable from the results of this year. ...I should like now to add a complete report of all my observations of sunspots up to the present, in which I have indicated the number of days of observation and the days when there were no spots to be seen, as well as the number of groups.

Year	No. of Clusters	Days when no Spots were observed	Observation Days
1826	118	22	277
1827	161	2	273
1828	225	0	282
1829	199	0	244
1830	190	1	217
1831	149	3	239
1832	84	49	270
1833	33	139	267
1834	51	120	273
1835	173	18	244
1836	272	0	200
1837	333	0	168
1838	282	0	202
1839	162	0	205
1840	152	3	263
1841	102	15	283
1842	68	64	307
1843	34	149	324

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Author and Curator: Dr. David P. Stern
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Last updated 25 November 2001

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#16a. Discovery of the Sunspot Cycle

Excerpts from Solar Observations During 1843 by Heinrich Schwabe, (Astronomische Nachrichten, vol. 20., no. 495, 1843)

Back to the Master List

Above is background material for archival reference only.