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Solar Cycle 2
Solar cycle 2 was the second solar cycle since 1755, when extensive recording of sunspot activity began. The solar cycle lasted 9 years, beginning in June 1766 and ending in June 1775. The maximum smoothed sunspot number observed during the solar cycle was 193.0 (September 1769), and the starting minimum was 18.6.SIDC Monthly Smoothed Sunspot Number. Sunspot observations by Alexander Wilson (astronomer), Alexander Wilson during this period established the Wilson effect. See also *List of solar cycles Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to start in 1755 when Rudolf Wolf began extensive reporting o ... References {{DEFAULTSORT:Solar Cycle 02 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilson Effect
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 is difficult to determine, but may be as large as 1,000 km. Sunspots result from the blockage of convective heat transport by intense magnetic fields. Sunspots are cooler than the rest of the photosphere, with effective temperatures of about 4,000°C (about 7,000°F). Sunspot occurrence follows an approximately 11-year period known as the solar cycle, discovered by Heinrich Schwabe in the 19th century. History 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 umb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 observed during the solar cycle was 144.1 (June 1761), and the starting minimum was 14.0. Solar 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 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. See also *List of solar cycles Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Cycle 3
Solar cycle 3 was the third solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 9.3 years, beginning in June 1775 and ending in September 1784. The maximum smoothed sunspot number observed during the solar cycle was 264.3 (May 1778), and the starting minimum was 12.0.SIDC Monthly Smoothed Sunspot Number. William Herschel began observing sunspots during this period. See also *List of solar cycles Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to start in 1755 when Rudolf Wolf began extensive reporting o ... References 3 {{sun-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Cycle
The solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surface. Over the period of a solar cycle, levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation from a period of minimum activity to a period of a maximum activity back to a period of minimum activity. The magnetic field of the Sun flips during each solar cycle, with the flip occurring when the solar cycle is near its maximum. After two solar cycles, the Sun's magnetic field returns to its original state, completing what is known as a Hale cycle. This cycle has been observed for centuries by changes in the Sun's appearance and by terrestrial phenomena such as aurora but was not clearly identified until 1843. Solar activity, driven by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunspot
Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. 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 they move across the surface of the Sun, with diameters ranging from to . Larger sunspots can be visible from Earth without the aid of a telescope. They may travel at relative speeds, or proper motions, of a few hundred meters per second when they first emerge. Indicating intense magnetic activity, sunspots accompany other active region phenomena such as coronal loops, prominences, and reconnection events. Most solar flares and coronal mas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoothed Sunspot Number
The Wolf number (also known as the relative sunspot number or Zürich number) is a quantity that measures the number of sunspots and groups of sunspots present on the surface of the Sun. History Astronomers have been observing the Sun recording information about sunspots since the advent of the telescope in 1609. However, the idea of compiling the information about the sunspot number from various observers originates in Rudolf Wolf in 1848 in Zürich, Switzerland. The produced series initially had his name, but now it is more commonly referred to as the international sunspot number series. The international sunspot number series is still being produced today at the observatory of Brussels. The international number series shows an approximate periodicity of 11 years, the solar cycle, which was first found by Heinrich Schwabe in 1843, thus sometimes it is also referred to as the Schwabe cycle. The periodicity is not constant but varies roughly in the range 9.5 to 11 years. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Wilson (astronomer)
Alexander Wilson (171416 October 1786) was a Scottish surgeon, type-founder, astronomer, mathematician and meteorologist. He was the first scientist to use kites in meteorological investigations. In 1784, his son Patrick Wilson succeeded him as Regius Professor of Practical Astronomy at the University of Glasgow. Early life Wilson was born in St Andrews, Fife, the son of Patrick Wilson, the town clerk. Alexander was educated at the University of St Andrews, graduating in 1733, aged 18, with an MA. He was first apprenticed to a physician in St Andrews where he became skilled in constructing mercury thermometers in glass. In 1737, he left for London to make his fortune, He found work as assistant to a French surgeon-apothecary, which included caring for his patients. During this time he was introduced to Lord Isla who like Wilson was interested in astronomy, and Wilson constructed instruments for Isla during 1738. After visiting a type foundry with a friend in London, he h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Solar Cycles
Solar cycles are nearly periodic 11-year changes in the Sun's activity that are based on the number of sunspots present on the Sun's surface. The first solar cycle conventionally is said to start in 1755 when Rudolf Wolf began extensive reporting of sunspot activity. The source data are the revised International Sunspot Numbers (ISN v2.0), as available at SILSO. Sunspot counts exist since 1610 but the cycle numbering is not well defined during the Maunder minimum. It was proposed that one cycle might have been lost in the late 18th century, but this remains not fully confirmed. Solar cycles can be reconstructed indirectly, using the radiocarbon Carbon-14, C-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and coll ... 14C proxy, for the last millennium. The smoothing is done using the traditional SIDC smo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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