The Modern Maximum, refers to the period of relatively high solar activity which began with

solar cycle 15 Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923. The maximum smoothed sunspot number observed dur ...

in 1914. It reached a maximum in

solar cycle 19 Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. " solar panels") ** Solar calendar, a calendar whose dates indica ...

during the late 1950s and may have ended with the peak of

solar cycle 23 Solar cycle 23 was the 23rd solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 12.3 years, beginning in August 1996 and ending in December 2008. The maximum smoothed sunspot number observed d ...

in 2000, as

solar cycle 24 Solar cycle 24 is the most recently completed solar cycle, the 24th since 1755, when extensive recording of solar sunspot activity began.Kane, R.P. (2002).Some Implications Using the Group Sunspot Number Reconstruction. ''Solar Physics'' 205(2), 3 ...

is recording, at best, very muted solar activity. Another proposed end date for the maximum is 2007, with the decline phase of Cycle 23. In any case the low solar activity of solar cycle 24 in the 2010s marked a new period of reduced solar activity. This maximum period is a natural example of

solar variation The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfac ...

, and one of many that are known from proxy records of past solar variability. The Modern Maximum reached a double peak once in the 1950s and again during the 1990s.

References

20th century 2000s Solar phenomena {{sun-stub