Sunspot
Videos
Sunspots are temporary spots on the Sun's surface that are darker than the surrounding area. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit conv
The Swedish 1-m Solar Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands
NASA's SDO Observes Largest Sunspot of the Solar Cycle
Sunspots 1302 Sep 2011 by NASA
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Solar cycle
Videos
The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of variations in the number of o
Sunspot
…Sunspots appear within active regions, usually in pairs of opposite magnetic polarity. Their number varies according to the approximately 11-year solar cycle. Individual sunspots or groups of sunspots may last anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as…
Samuel Heinrich Schwabe (1789–1875), German astronomer, discovered the solar cycle through extended observations of sunspots.
Rudolf Wolf (1816–1893), Swiss astronomer, carried out historical reconstruction of solar activity back to the 17th century.
A drawing of a sunspot in the Chronicles of John of Worcester, c. 1100
An overview of three solar cycles shows the relationship between the solar cycle, galactic cosmic rays, and the state of Earth's near-space environment.