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3-11 10-6 Solar cycle 20: 1964 – Oct 14.3 1968 – Nov 157 86 4-1 11-5 Solar cycle 21: 1976 – Mar 17.8 1979 – Dec 233 111 3-9 10-6 Solar cycle 22: 1986 – Sep 13.5 1989 – Nov 213 106 3-2 9-11 Solar cycle 23: 1996 – Aug 11.2 2001 – Nov 180 82 5-3 12-4 Solar cycle 24: 2008 – Dec 2.2 2014 – Apr 116 49 5-4 11-0 Solar cycle 25: 2019 ...
Solar cycle 23 lasted 11.6 years, beginning in May 1996 and ending in January 2008. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve-month period) observed during the solar cycle was 120.8 (March 2000), and the minimum was 1.7. [29] A total of 805 days had no sunspots during this cycle. [30] [31] [32]
The sun emits the largest solar flare of this 11-year cycle, as imaged by NASA's Solar Dynamics Observatory on October 3. NASA/SDO NASA says the sun is in the highly active "maximum phase" of its ...
Solar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%. [2] On average, the solar cycle takes about 11 years to go from one solar maximum to the next, with duration observed varying from 9 to ...
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 they move across the surface of the Sun, with diameters ranging from 16 km (10 mi) [3] to 160,000 km (100,000 mi). [4]
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] Sunspots usually appear as pairs with opposite magnetic polarity. [31]
At a solar-cycle minimum, the toroidal field is, correspondingly, at minimum strength, sunspots are few in number, and the poloidal field is at its maximum strength. With the rise of the next 11-year sunspot cycle, magnetic energy shifts back from the poloidal to the toroidal field, but with a polarity that is opposite to the previous cycle.
In 2002, Lean et al. [41] stated that while "There is ... growing empirical evidence for the Sun's role in climate change on multiple time scales including the 11-year cycle", "changes in terrestrial proxies of solar activity (such as the 14C and 10Be cosmogenic isotopes and the aa geomagnetic index) can occur in the absence of long-term (i.e ...