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  2. Sunspot - Wikipedia

    en.wikipedia.org/wiki/Sunspot

    Sunspot number is correlated with the intensity of solar radiation over the period since 1979, when satellite measurements became available. The variation caused by the sunspot cycle to solar output is on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W·m −2 compared with 1366 W·m −2 for the average solar constant).

  3. Solar cycle - Wikipedia

    en.wikipedia.org/wiki/Solar_cycle

    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 surface.

  4. List of solar cycles - Wikipedia

    en.wikipedia.org/wiki/List_of_solar_cycles

    List of solar cycles. 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]

  5. Solar cycle 25 - Wikipedia

    en.wikipedia.org/wiki/Solar_cycle_25

    Solar cycle 25 is the current solar cycle, the 25th since 1755, when extensive recording of solar sunspot activity began. It began in December 2019 with a minimum smoothed sunspot number of 1.8. [2] It is expected to continue until about 2030. [3][4]

  6. Solar maximum - Wikipedia

    en.wikipedia.org/wiki/Solar_maximum

    Solar maximum is the regular period of greatest solar activity during the Sun 's 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%. [2] On average, the solar cycle takes about 11 years to go from one solar maximum to the next, with duration observed varying from 9 ...

  7. Solar phenomena - Wikipedia

    en.wikipedia.org/wiki/Solar_phenomena

    The image shows light with a wavelength of 304 angstroms. Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. They take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, [1] coronal heating and sunspots. These phenomena are believed to be generated by a helical dynamo ...

  8. Solar cycle 24 - Wikipedia

    en.wikipedia.org/wiki/Solar_cycle_24

    Solar cycle 25 (2019-present) NASA Solar Cycle 24 Sunspot Number Prediction. Solar cycle 24 is the most recently completed solar cycle, the 24th since 1755, when extensive recording of solar sunspot activity began. [1][2] It began in December 2008 with a minimum smoothed sunspot number of 2.2, [3][failed verification] and ended in December 2019 ...

  9. Solar observation - Wikipedia

    en.wikipedia.org/wiki/Solar_observation

    Sunspots had some importance in the debate over the nature of the Solar System. They showed that the Sun rotated, and their comings and goings showed that the Sun changed, contrary to Aristotle, who had taught that all celestial bodies were perfect, unchanging spheres. Sunspots were rarely recorded between 1650 and 1699.