Space

150 years of sunspots

Every sunspot group observed since 1874, plotted by the latitude where it appeared. The pattern draws itself: each 11-year cycle opens near 30 degrees, drifts to the equator, and dies there as the next cycle opens above it.

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Data & source

Source: the Greenwich Photoheliographic Results and their USAF/NOAA continuation, compiled by NASA Marshall · public domain · fetched —. One column per solar rotation (27.3 days) from 1874 to 2016 — that is where this compilation ends, so the current cycle is not here. Latitudes are the file's 50 equal-area strips (equal steps in the sine of latitude); values are sunspot area within each strip, in millionths of the visible hemisphere. Cycle numbers are marked at their accepted minima.