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Sunspot activity has been measured using the Wolf number for about 300 years. This index (also known as the Zürich number) uses both the number of sunspots and the number of sunspot groups to compensate for measurement variations. A 2003 study found that sunspots had been more frequent since the 1940s than in the previous 1150 years. [30]
Sunspot number is correlated with the intensity of solar radiation over the period since 1979, when satellite measurements became available. The variation caused by the sunspot cycle to solar output is on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W·m −2 compared with 1366 W·m −2 for the average solar constant).
In astronomy, the Wilson effect is the perceived depression of a sunspot's umbra, or center, in the Sun's photosphere. The magnitude of the depression for the umbra is between 500 and 1000 km, with an average of 600 km. [1] Sunspots result from the blockage of convective heat transport by intense magnetic fields. Sunspots are cooler than the ...
CMEs often form around sunspots, although scientists aren’t entirely sure why. Sunspot formation is cyclical, and the current solar cycle has reached the highest number of sunspots since 2001 ...
The total solar irradiance (TSI) panel shows the PMOD composite of observations [59] with a modelled variation from the SATIRE-T2 model of the effect of sunspots and faculae [53] with the addition of a quiet -Sun variation (due to sub-resolution photospheric features and any solar radius changes) derived from correlations with comic ray fluxes ...
Schwabe continued to observe the sunspot cycle for another 23 years, until 1867. In 1852, Rudolf Wolf designated the first numbered solar cycle to have started in February 1755 based on Schwabe's and other observations. [6] Wolf also created a standard sunspot number index, the Wolf number, which continues to be used today.
About 55 earthquakes a day – 20,000 a year – are recorded by the National Earthquake Information Center. A quick guide to how they are measured. Earthquakes happen all the time, you just can't ...
A sunspot this large is easy enough to see from Earth; all that is needed is a solar filter or pair of eclipse glasses to protect your eyes from the sun's dangerous rays. Sunspot AR3664 compared ...