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The maximum smoothed sunspot number observed during the solar cycle was 285.0, in March 1958 (the highest on record [3]), and the starting minimum was 5.1. [4] During the minimum transit from solar cycle 19 to 20, there were a total of 227 days with no sunspots. This was the lowest number since 1850. [5] [6] [7]
Solar cycles last typically about eleven years, varying from just under 10 to just over 12 years. Over the solar cycle, sunspot populations increase quickly and then decrease more slowly. The point of highest sunspot activity during a cycle is known as solar maximum, and the point of lowest activity as solar minimum.
Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to have started in 1755. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. [1]
Earlier this month, NOAA reported that preliminary observations had found 299 sunspots that all appeared within 24 hours — the highest daily sunspot record in over 22 years if confirmed.
A prediction for Sunspot Cycle 24 (2008-2020) gives a smoothed sunspot number maximum of about 66 in the Summer of 2013. Current observations make this the smallest sunspot cycle since records began in the 1750s. [1] Solar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle.
400 year sunspot history, including the Maunder Minimum "The prediction for solar cycle 24 gave a smoothed sunspot number maximum of about 69 in the late Summer of 2013. . The smoothed sunspot number reached 68.9 in August 2013 so the official maximum was at least that h
Solar cycle 21 was the 21st solar cycle since 1755, when extensive recording of solar sunspot activity began. [1] [2] The solar cycle lasted 10.5 years, beginning in March 1976 and ending in September 1986. The maximum smoothed sunspot number observed during the solar cycle was 232.9, in December 1979, and the starting minimum was 17.8. [3]
Four solar flares occurred within 5 days from sunspot AR 12192, which is both the largest sunspot of solar cycle 24 and the largest since 1990. On October 19 there was a major X1.1-class solar flare. On October 22 an M8.7-class flare was followed by an X1.6 event.