Solar minimum

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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.

Solar minimum and solar maximum--"Solar Min" and "Solar Max" for short--are two extremes of the sun's 11-year activity cycle. At maximum, the sun is peppered with spots, 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, disrupted satellite functions and communications, malfunctioning GPS receivers--these are just a few of the things that can happen during Solar Max.

Solar minimum is different. Sunspots are fewer--sometimes days or weeks go by without a spot. Solar flares subside. It's a safer time to travel through space, and a less interesting time to watch polar skies.

[edit] Characteristics of solar minimum

Solar minimum is characterized by a period of minimum solar activity with little, 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.