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Big Sunspots

Nature volume 145, page 66 (13 January 1940) | Download Citation



A BIG group of sunspots, originating about January 1 and growing rapidly, crossed the sun's central meridian on January 5 and reached the west limb on January 12. Between January 2 and 4, the area increased tenfold and measured 1,300 millionths of the sun's hemisphere on the latter date. Still expanding on January 5, the spots were clearly seen with the naked eye through the morning mist. In structure, the group was a typical stream with leader and follower spots and subsidiary spots in between. This group is the largest since last September, and indicates that, although the maximum of the 11-year cycle is past, the sun is still generally active.

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