Solar minimum

Solar minimum is the period of least solar activity in the solar cycle of the sun. During this time, sunspot and solar flare activity diminishes, and often does not occur for days at a time. The date of the minimum is described by a smoothed average over 12 months of sunspot activity, so identifying the date of the solar minimum usually can only happen 6 months after the minimum takes place.

Solar minimum is contrasted with the solar maximum, where there may be hundreds of sunspots.

olar minimum and solar maximum

Solar minimums and maximums are the two extremes of the sun's 11-year activity cycle. At a maximum, the sun is peppered with sunspots, solar flares erupt, and the sun hurls billion-ton clouds of electrified gas into space. It's a good time for sky watchers who enjoy auroras, but not so good for astronauts who have to be wary of radiation storms. Power outages, satellite function and communication disruptions, and GPS receiver malfunctions are just a few of the things that can happen during a solar max. At a solar minimum, there are fewer sunspots and solar flares subside. Sometimes, days or weeks go by without a spot. It is a safer time to travel through space, but a less interesting time to watch polar skies.

Characteristics of solar minimum

Solar minimum is characterized by a period of minimum solar activity with few, if any, sunspots. Generally, this is the safest time for astronauts to do their missions due to an associated decrease in solar radiation. During solar minimum, scientists can predict the next two solar cycles using the solar "conveyor belt." If the conveyor belt is moving rapidly it will sweep up lots of old magnetic fields on the sun's surface to the sun's center, eventually returning to the surface as lots of new sunspots. The opposite is true when the conveyor belt is moving slowly since fewer old magnetic fields are being swept down. Using this method of forecasting, Solar Cycle 25 will be a very mild cycle with few sunspots even during solar maximum.

References

http://science.nasa.gov/headlines/y2006/10may_longrange.htm Solar Cycle 25 peaking around 2022 could be one of the weakest in centuries.

ee also

* Maunder Minimum