butterfly diagram
  • Chart of the latitude of sunspots against time. As the years pass through different sunspot cycles it is seen that sunspots tend to start the cycle near the poles and then appear in larger numbers nearer the Sun’s equator as the cycle proceeds. The diagram produced looks like a series of pairs of butterfly wings. The spots tend to start at 30–40° latitude and finish at about 5°. Spots in polar regions or at the equator are comparatively rare. The first butterfly diagrams were drawn by E W Maunder of the Royal Greenwich Observatory in England.

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