"Solar cycle 11 Solar cycle 11 was the eleventh solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 11.8 years, beginning in March 1867 and ending in December 1878. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 234.0 (August 1870), and the starting minimum was 9.9. During the minimum transit from solar cycle 11 to 12, there were a total of 1028 days with no sunspots (the highest recorded of any cycle transit to date). Strong auroral displays were observed in October 1870, February 1872, and August 1872."
"Sunspot Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear 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 they move across the surface of the Sun, with diameters ranging from to . The larger variety are visible from Earth"
"called sunspots and in solar prominences. The magnetic field also varies in time and location. The quasi-periodic 11-year solar cycle is the most prominent variation in which the number and size of sunspots waxes and wanes. Sunspots are visible as dark patches on the Sun's photosphere, and correspond to concentrations of magnetic field where the convective transport of heat is inhibited from the solar interior to the surface. As a result, sunspots are slightly cooler than the surrounding photosphere, and, so, they appear dark. At a typical solar minimum, few sunspots are visible, and occasionally none can be seen at"
"the 1940s than in the previous 1150 years. Sunspots usually appear as pairs with opposite magnetic polarity. Detailed observations reveal patterns, in yearly minima and maxima and in relative location. As each cycle proceeds, the latitude of spots declines, from 30–45° to around 7° after the solar maximum. This latitudinal change follows Spörer's law. For a sunspot to be visible to the human eye it must be about 50,000 km in diameter, covering or 700 millionths of the visible area. Over recent cycles, approximately 100 sunspots or compact sunspot groups are visible from Earth. Sunspots expand and contract as they"
"sunspots and groups of sunspots during specific intervals. The 11-year solar cycles are numbered sequentially, starting with the observations made in the 1750s. George Ellery Hale first linked magnetic fields and sunspots in 1908.<ref name=""doi10.1086/141602""></ref> Hale suggested that the sunspot cycle period is 22 years, covering two periods of increased and decreased sunspot numbers, accompanied by polar reversals of the solar magnetic dipole field. Horace W. Babcock later proposed a qualitative model for the dynamics of the solar outer layers. The Babcock Model explains that magnetic fields cause the behavior described by Spörer's law, as well as other effects, which"
"concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days to weeks. In 2001, observations from the Solar and Heliospheric Observatory (SOHO) using sound waves traveling below the photosphere (local helioseismology) were used to develop a three-dimensional image of the internal structure below sunspots; these observations show that a powerful downdraft underneath each sunspot, forms a rotating vortex that sustains the concentrated magnetic field. Sunspot activity cycles are about every eleven years, with some variation in length. Over the solar cycle, sunspot populations rise quickly and then fall more slowly. The point of highest sunspot activity during"
"at the same time that meteorological observation was establishing itself as a scientific pursuit to enable daily weather forecasting. The appearance of spots on the surface of the sun had been the source of conjecture for a long time. Around the middle of the 19th century it was recognised that the number of sunspots increased and decreased on a regular cycle of around 11 years. The hypothesis was that as the sun dominates our experience of weather, then the sunspot cycle might set in motion regular changes in the Earth's climate. Consequently, during the late 19th and early 20th centuries,"
"all. Those that do appear are at high solar latitudes. As the solar cycle progresses towards its maximum, sunspots tend form closer to the solar equator, a phenomenon known as Spörer's law. The largest sunspots can be tens of thousands of kilometers across. An 11-year sunspot cycle is half of a 22-year Babcock–Leighton dynamo cycle, which corresponds to an oscillatory exchange of energy between toroidal and poloidal solar magnetic fields. At solar-cycle maximum, the external poloidal dipolar magnetic field is near its dynamo-cycle minimum strength, but an internal toroidal quadrupolar field, generated through differential rotation within the tachocline, is near"
"sunspot butterfly diagram for cycles 3 and 4, although total sunspot numbers only show a single-peaked distribution. Solar cycle 4 Solar cycle 4 was the fourth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 13.6 years, beginning in September 1784 and ending in April 1798 (thus overlapping the Dalton Minimum). The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 235.3 (in February 1788), and the starting minimum was 15.9. There are some recent speculations that cycle 4, the longest solar cycle since 1755, was actually two cycles, based"
"Solar cycle 20 Solar cycle 20 was the twentieth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 11.4 years, beginning in October 1964 and ending in March 1976. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 156.6 (November 1968), and the starting minimum was 14.3. During the minimum transit from solar cycle 20 to 21, there were a total of 272 days with no sunspots. Comparison with other cycles shows that geomagnetic activity during the declining phase of cycle 20 (1973–1975) was unusually high. Data from solar"
"Thus the Sun emits about 2.2 billion times the amount of radiation that is caught by Earth, in other words about 3.86×10 watts. Space-based observations of solar irradiance started in 1978. These measurements show that the solar constant is not constant. It varies with the 11-year sunspot solar cycle. When going further back in time, one has to rely on irradiance reconstructions, using sunspots for the past 400 years or cosmogenic radionuclides for going back 10,000 years. Such reconstructions show that solar irradiance varies with distinct periodicities. These cycles are: 11 years (Schwabe), 88 years (Gleisberg cycle), 208 years (DeVries"
"Solar cycle The solar cycle or solar magnetic activity cycle is the nearly periodic 11-year change in the Sun's activity (including changes in the levels of solar radiation and ejection of solar material) and appearance (changes in the number and size of sunspots, flares, and other manifestations). They have been observed (by changes in the sun's appearance and by changes seen on Earth, such as auroras) for centuries. The changes on the Sun cause effects in space, in the atmosphere, and on Earth's surface. While it is the dominant variable in solar activity, aperiodic fluctuations also occur. Solar cycles have"
"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 . A total of 805 days had no sunspots during this cycle. Because the solar cycle reflects magnetic activity, various magnetically driven solar phenomena follow the solar cycle, including sunspots and coronal mass ejections. The Sun's apparent surface, the photosphere, radiates more actively when there are more sunspots. Satellite monitoring of solar luminosity revealed a direct relationship between the Schwabe cycle and luminosity with"
"Solar cycle 23 Solar cycle 23 was the 23rd solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 12.3 years, beginning in August 1996 and ending in December 2008. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 180.3 (November 2001), and the starting minimum was 11.2. During the minimum transit from solar cycle 23 to 24, there were a total of 817 days with no sunspots. Compared to the last several solar cycles, it was fairly average in terms of activity. Large solar flares occurred on 7 September"
"a temperature of , together with a warm spot of . Sunspot Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear 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 they move across the surface of the Sun, with diameters"
"cycle, and values of the solar flux during this cycle turned out to be particularly high. Solar cycle 18 Solar cycle 18 was the eighteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.2 years, beginning in February 1944 and ending in April 1954. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 218.7 (May 1947), and the starting minimum was 12.9. During the minimum transit from solar cycle 18 to 19, there were a total of 446 days with no sunspots. Cycle 18 was characterized by ""giant"""
"Solar cycle 17 Solar cycle 17 was the seventeenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.4 years, beginning in September 1933 and ending in February 1944. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 198.6 (April 1937), and the starting minimum was 5.8. During the minimum transit from solar cycle 17 to 18, there were a total of 269 days with no sunspots. A great aurora display was seen all over Europe on 25 January 1938, as far south as Portugal and Sicily, frightening many"
"Solar cycle 4 Solar cycle 4 was the fourth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 13.6 years, beginning in September 1784 and ending in April 1798 (thus overlapping the Dalton Minimum). The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 235.3 (in February 1788), and the starting minimum was 15.9. There are some recent speculations that cycle 4, the longest solar cycle since 1755, was actually two cycles, based on the appearance of new sunspots at high solar latitudes in 1793–1796 and a reconstruction of the"
"Solar cycle 18 Solar cycle 18 was the eighteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.2 years, beginning in February 1944 and ending in April 1954. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 218.7 (May 1947), and the starting minimum was 12.9. During the minimum transit from solar cycle 18 to 19, there were a total of 446 days with no sunspots. Cycle 18 was characterized by ""giant"" sunspots. The recording of the 10.7 cm (2800 MHz) solar radio flux began partway during this"
"the Sun's photosphere and correspond to concentrations of magnetic field. At a typical solar minimum, few or no sunspots are visible. Those that do appear are at high solar latitudes. As the solar cycle progresses towards its maximum, sunspots tend to form closer to the solar equator, following Spörer's law. The 11-year sunspot cycle is half of a 22-year Babcock–Leighton solar dynamo cycle, which corresponds to an oscillatory exchange of energy between toroidal and poloidal solar magnetic fields. At solar-cycle maximum, the external poloidal dipolar magnetic field is near its dynamo-cycle minimum strength, but an internal toroidal quadrupolar field, generated"
"people. Some thought that the red glow indicated large fires, while others linked it to the Fátima prophecies. An aurora was visible over New York on 3 April 1940. Solar cycle 17 Solar cycle 17 was the seventeenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.4 years, beginning in September 1933 and ending in February 1944. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 198.6 (April 1937), and the starting minimum was 5.8. During the minimum transit from solar cycle 17 to 18, there were a"
"are twisted by the Sun's rotation. Sunspot number also changes over long periods. For example, from 1900 to the 1960s, the solar maxima trend of sunspot count was upwards; for the following decades it diminished. However, the Sun was last as active as this period over 8,000 years ago. Sunspots 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 relatively small, on the order of 0.1% of the solar constant (a peak-to-trough range of 1.3 W·m compared with 1366"
"occurrence follows an approximately 11-year period known as the solar cycle, discovered by Heinrich Schwabe in the 19th century. Wilson effect In 1769, during solar cycle 2, Scottish astronomer Alexander Wilson, working at the Macfarlane Observatory, noticed that the shape of sunspots noticeably flattened as they approached the Sun's limb due to solar rotation. These observations showed that sunspots were features on the solar surface, as opposed to minor planets or objects above it. Moreover, he observed what is now termed the Wilson effect: the penumbra and umbra vary in the manner expected by perspective effects if the umbrae of"
"Babcock Model The Babcock Model describes a mechanism which can explain magnetic and sunspot patterns observed on the Sun. The modern understanding of sunspots starts with George Ellery Hale, who linked magnetic fields and sunspots. Hale suggested that the sunspot cycle period is 22 years, covering two polar reversals of the solar magnetic dipole field. Horace W. Babcock proposed in 1961 a qualitative model for solar dynamics. On the largest scale, the Sun supports an oscillatory magnetic field, with a quasi-steady periodicity of 22 years. This oscillation is known as the Babcock-Leighton dynamo cycle, amounting to the oscillatory exchange of"
"the mean length of the cycle from about a decade to 11.11 years. However, he could not find enough observations before 1755 to reliably identify cycles, hence the 1755–1766 cycle is conventionally numbered as cycle #1. Wolf published his results in 1852. Solar cycle 1 Solar cycle 1 was the first solar cycle since extensive recording of solar sunspot activity began. The solar cycle lasted 11.3 years, beginning in February 1755 and ending in June 1766. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 144.1 (June 1761), and the starting minimum was 14.0. Cycle #1"
"Solar cycle 1 Solar cycle 1 was the first solar cycle since extensive recording of solar sunspot activity began. The solar cycle lasted 11.3 years, beginning in February 1755 and ending in June 1766. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 144.1 (June 1761), and the starting minimum was 14.0. Cycle #1 was discovered by Johann Rudolph Wolf who, inspired by the discovery of the solar cycle by Heinrich Schwabe in 1843, collected all available sunspot observations going back to the first telescopic observations by Galileo. He was able to improve Schwabe's estimate of"
"Solar cycle 9 Solar cycle 9 was the ninth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 12.4 years, beginning in July 1843 and ending in December 1855. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 219.9 (February 1848), and the starting minimum was 17.6. During the solar cycle minimum transit from solar cycle 9 to solar cycle 10, there were a total of 655 days with no sunspots. Solar cycle 9 began in 1843, the year that Heinrich Schwabe discovered the sunspot cycle. During this cycle,"
"a cycle is known as solar maximum, and the point of lowest activity as solar minimum. This period is also observed in most other solar activity and is linked to a variation in the solar magnetic field that changes polarity with this period. Early in the cycle, sunspots appear in the higher latitudes and then move towards the equator as the cycle approaches maximum, following Spörer's law. Spots from two adjacent cycles can co-exist for some time. Spots from adjacent cycles can be distinguished by direction of their magnetic field. The Wolf number sunspot index counts the average number of"
"sunspot activity was then concentrated in the southern hemisphere of the Sun, except for the last cycle when the sunspots appeared in the northern hemisphere, too. According to Spörer's law, at the start of a cycle, spots appear at ever lower latitudes until they average at about latitude 15° at solar maximum. The average then continues to drift lower to about 7° and after that, while spots of the old cycle fade, new cycle spots start appearing again at high latitudes. The visibility of these spots is also affected by the velocity of the Sun's surface rotation at various latitudes:"
"Solar cycle 16 Solar cycle 16 was the sixteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.1 years, beginning in August 1923 and ending in September 1933. The maximum smoothed sunspot number (SIDC formula) observed during the solar cycle was 130.2 (April 1928), and the starting minimum was 9.4. During the minimum transit from solar cycle 16 to 17, there were a total of 568 days with no sunspots. Newspaper reports during this period note effects on telegraph systems, but also (in March 1924, January 1926, October 1926, and October 1927)"
"followed by a weak maximum at around 2022. Instead, the sunspot cycle in 2010 was still at its minimum, when it should have been near its maximum, demonstrating its unusual weakness. Cycle 24's minimum occurred around December 2008 and the next maximum was predicted to reach a sunspot number of 90 around May 2013. The monthly mean sunspot number in the northern solar hemisphere peaked in November 2011, while the southern hemisphere appears to have peaked in February 2014, reaching a peak monthly mean of 102. Subsequent months declined to around 70 (June 2014). In October 2014, sunspot AR 12192"
"Léon Foucault. Sunspots, as well as the limb darkening effect, are visible in their daguerrotypes. Photography assisted in the study of solar prominences, granulation and spectroscopy. Charles A. Young first captured a prominence in 1870. Solar eclipses were also photographed, with the most useful early images taken in 1851 by Berkowski in 1860 by De la Rue's team in Spain. Early estimates of the Sun's rotation period varied between 25 and 28 days. The cause was determined independently in 1858 by Richard C. Carrington and Spörer. They discovered that the latitude with the most sunspots decreases from 40° to 5°"
"about climate change on the Earth. More specifically, varying amounts of sun activity, including sunspots, solar flares, solar wind, and massive solar radiation, can all be grouped together as geomagnetic storms, which together, act to affect Earth's climate. Our sun has a solar activity cycle of about 11 years. During which time, the sun gets sunspots, shoots off solar flares, and blasts earth with solar wind and geomagnetic activity. Despite the appearance that these events seem random, they do overall follow a fairly steady cycle of approximately 11 years. The difference in average solar irradiation received by the earth due"