The Sun's activity follows an approximately 11-year cycle. For the current cycle, number 23, the minimum, or low point in the Sun's activity occurred in May 1996. Maximum—the peak of the Sun's activity—is expected to occur in May 2000, according to NASA's Marshall Solar Activity Future Estimate (MSAFE) Model.
Our ability to identify the start and approximate profile of a new solar cycle, and to produce viable, consistent, and timely estimates of its behavior, is considerably important since the space environment and associated geophysical effects are all, to one degree or another, affected by aspects of the Sun's activity. Early identification of the magnitude and projected time of minimum (and maximum) amplitude of a new cycle occupies many researchers, especially as the peaks and valleys of the Sun's activity near. Identification of the date and minimum amplitude is particularly important because it is used in models that predict future levels of solar activity as related to spacecraft orbital lifetime predictions, flare frequency, number and severity of geomagnetic storms, and radiation and ionospheric models.