Science Forums 2

[Turtle]

Originally Posted by REASON

I also wonder if the lesser amount of sunspots on the charts from 1880 to 1940 are actually indicative of less sunspots, or the technological ability to detect them.

Any ideas on that?

First, sorry for the huge butterfly! I have the darndest time inserting images. To the question of accuracy for the period you noted, adjacent to the Butterfly diagram is this descriptive text:

Originally Posted by NASA

...Detailed observations of sunspots have been obtained by the Royal Greenwich Observatory since 1874. These observations include information on the sizes and positions of sunspots as well as their numbers. These data show that sunspots do not appear at random over the surface of the sun but are concentrated in two latitude bands on either side of the equator. ...

Of the earlier periods back to Galileo, this is given:

Originally Posted by NASA

Early records of sunspots indicate that the Sun went through a period of inactivity in the late 17th century. Very few sunspots were seen on the Sun from about 1645 to 1715 (38 kb JPEG image). Although the observations were not as extensive as in later years, the Sun was in fact well observed during this time and this lack of sunspots is well documented.

NASA/Marshall Solar Physics