Solar Variation Gallery

The variations in a number of solar activity proxies over the last three solar cycles. Except for the daily variations in total solar irradiance, other quantities are shown as annual averages.

The history of sunspot observations over the last 400 years. Though sunspot activity has been high during the recent period, the lack of a discernible trend is one line of argument against solar activity playing a dominant role in recent global warming. By contrast, low solar activity during the Maunder Minimum may have been a major cause of the Little Ice Age.

Comparison of sunspot number and beryllium-10 concentration measured in a polar ice core. Proxies such as these are used to extend our understand of solar activity variations to periods where no direct measurement of total solar irradiance is available.

Milankovitch cycles, occurring over tens and hundreds of thousands of years, are variations in the flux and distribution of solar radiation reaching the Earth's surface due to predictable variations in the Earth's orbit, characterized by changes in precession, obliquity, and eccentricity. Such changes are believed to be principally responsible for the waxing and waning of glacial periods during the present ice age.