The Solar Physics
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Illustration of the Sun internal mechanism!
1- The Sunspots Mechanism
Solar Physics
The Sun was feared by earlier human entities, to extent of worship, the worship was worldwide phenomena, in ancient African groups lead by the Egyptians, Romans, Greeks, Indians, Chinese, Aztec and Indonesian, all had worshiped the Sun in different manners. Humanity progression and divine intervention, lead to rational balance, developed into scientific criteria to better understand and reveal secrets behind natural phenomena, among which was the sun.
The sunspots, as black spots and shapes on solar disk, has deep historical background in different civilizations, reflecting levels of progress of human societies, and importance of solar activities as part of human knowledge.
In this section of the website, we presented how we look into major solar phenomena, such as, “The Sunspots Mechanism (where and how it is generated)”, “Solar flare (What is it, how it is generated)”, and “The Spicule”, among others, we first started with Sunspots, others will soon followed:
Solar Physics: Time Line of Great Achievements
1223 BC - The oldest eclipse record: Found on a clay tablet in the ancient city of Ugarit, (in what is now Syria), with two plausible dates usually cited: 3 May 1375 BC or 5 March 1223 BC.
ca. 800 BC - The first plausible recorded sunspot observation: Oldest sunspot record found in the Book of Changes in China.
ca. 350 BC - Sun circling under a sheltering sky: The physical model of the cosmos developed by Aristotle (384-322).
ca. 200 BC - The distance to the Sun: First attempt to determine Sun-Earth distance by Aristarchus of Samos (ca. 310-230 BC).
968 - The first mention of the solar corona: Solar corona, which is visible at any solar eclipse, first ambiguously mentioned by the Byzantine historian Leo Diaconus (ca. 950-994).
1128 - The first sunspot drawing: The first sunspot drawing, from a sighting on Saturday, 8 December 1128, in the Chronicles of John of Worcester (d, 1140), one of contributed monks
1185 - The first description of solar prominences: Description by the Russian Chronicle of Novgorod, in 1 May 1185.
1543 - The Sun moves to center stage: The debate between planetary astronomy of Ptolemy and the new planetary model with the Sun placed in center by Nicholas Copernicus (1473-1543).
1609 - The Sun in focus: Johannes Kepler (1571-1630), using Tycho Brahe (1546-1601) observations realized the elliptical orbital paths of planets around the Sun.
1610 - First telescopic observations of sunspots: Johann Goldsmid (1587-1616, a.k.a. Fabricius) in Holland, Thomas Harriot (1560-1621) in England, Galileo Galilei (1564-1642) in Italy, and the Jesuit Christoph Scheiner (1575-1650) in Germany, simultaneously used the invented telescope to explored the sunspots.
1644 - The Sun as a star: The Sun as center of Universe in Copernican system, was rejected by philosophers like René Descartes (1596-1650), and the Sun became normal star.
1645-1715 - Sunspots vanish: Sunspots observed actively by the German Johannes Hevelius (1611-1687) and the French Jesuit Jean Picard (1620-1682).
1687 - The mass of the Sun: The first estimate of the Sun's mass was due to Isaac Newton (1642-1727).
1774-1801 - The physical nature of sunspots: Galileo thought sunspots are cloud-like structures in the solar atmosphere, while Scheiner believed them to be dense objects embedded in the Sun's luminous atmosphere. In 1774, Wilson suggested that sunspots were opening in the Sun's luminous atmosphere.
1796 - The nebular hypothesis: William Herschel (1738-1822) discovered diffuse cloud-like structures, or dubbed Nebulae. While Pierre Simon de Laplace (1749-1827) formulated the nebular hypothesis.
1800 - The Sun's invisible radiation: In 1800, William Herschel extended Newton's experiment (separating sunlight by prism) and detected the microwaves.
1802 - Black lines in the Sun: William Hyde Wollaston(1766-1828), noticed other dark lines (f,g) that did not appear to delineate colors.
1817 - Solar spectroscopy is born: Joseph von Fraunhofer (1787-1826) independently rediscovered the 'dark lines' in the solar spectrum. And intended to use the lines as wavelength standards to determine the index of refraction of optical glasses. Other think Fraunhofer lines could be used to infer properties of the solar atmosphere.
1838 - The solar constant: Is a measure of the sun's luminosity, which as “amount of energy incident per second on one square meter of the outer terrestrial atmosphere”, when the Earth is at one astronomical unit (149,598,500 km) from the Sun.
1843 - The sunspot cycle: Sunspots observers showed sunspots rarely appear outside of a latitudinal band of about ± 30° centered about the solar equator. In 1843 Samuel Heinrich Schwabe (1789-1875), discovered the cyclic number of sunspot he estimated to be of 10 years.
1845 - The first solar photograph: Developed in the 1830's by J. N. Niepce (1765-1833) and Louis Daguerre (1789-1851), and relied on the exposure of a thin iodine layer deposited on a silver substrate.
1848 - The sunspot number: The sunspots drawing by Johann Hieronymus Schroeter (1745-1816), between 1785 and 1795, became the primary source for Wolf's reconstruction of activity cycle number 4 (1785--1798)
1852 - The sunspot cycle is linked to geomagnetic activity: Edward Sabine (1788-1883) announced that: Sunspot cycle period was "absolutely identical" to geomagnetic activity. It was independently arrived to by Rudolf Wolf (1816-1893), Jean-Alfred Gautier (1793-1881), and Johann von Lamont (1805-1879).
1858-1859 - The solar differential rotation: Early nineteenth century solar astronomers were increasingly intrigued at previously tracked varied anywhere from 25 to 28 days. The difference was larger than good observers can track sunspot motion.
1859 - First observation of a solar flare: On 1 September 1859, amateur astronomer Richard C. Carrington (1826-1875) noticed two rapidly brightening patches of light near the middle of a sunspot group he was studying. The patches dimmed again while moving with respect to the active region, finally disappeared. This was independently observed by British astronomer R. Hodgson (1804-1872).
1859 - The chemical composition of the Sun: In late 1850s, chemist Robert Wilhelm Bunsen (1811-1899) and theoretical physicist Gustav Kirchhoff (1824-1887), simultaneous compare observations of the solar spectrum and laboratory flame spectra, they showed that (bright) emission lines in heated gases coincide with (dark) absorption lines seen when observing white light shining through the same cool gas. This established the empirical basis for identification of the dark lines seen in the solar spectrum. By this Kirchhoff demonstrate the existence in the Sun of a large number of chemical elements, mostly metals. Hydrogen was identified spectroscopically in 1862 by A. Ångström (1814-1874), but it is in the 1920's, that Hydrogen was recognized as the most abundant solar constituent.
1860 - First observations of a coronal mass ejection: Strange drawings of solar peripheries, at the eclipse of 18 July 1860 include depictions of peculiar features in the lower right portion of the corona; they probably represent the first record of a Coronal Mass Ejection (CME).
1881 - The solar constant, again: After various solar observing expeditions to mountaintops, it becomes clear that the Earth's atmosphere absorbs a significant portion of the sun's luminosity. Consequently, solar constant was moved to the highest practical altitudes.
1908 - The magnetic nature of sunspots: In 1907-1908, by measuring the Zeeman splitting in magnetically sensitive lines in the spectra of sunspots and detecting the polarization of the split spectral components, George Ellery Hale (1868-1938), provided the first unambiguous and quantitative demonstration that sunspots are the seats of strong magnetic fields.
1919 - The Sun's magnetic cycle: Decade following above discovery, George Ellery Hale (1868-1938) and his collaborators showed that large sunspots pairs almost always (1) show the same magnetic polarity pattern in each solar hemisphere, (2) show opposite polarity patterns between the North and South solar hemispheres, and (3) these polarity patterns are reversed from one sunspot cycle to the next. Indicating that the physical magnetic cycle has a period of twice the sunspot cycle period.
1931 - The coronagraph: Difficulty of longer, reachable total solar eclipses led in 1931 the French solar physicist Bernard Lyot (1897-1952), to designed an instrument now known as the coronagraph, that allowed observation of the corona at full daylight
1941- The million-degree solar corona: In 1930, coronagraphic observation by Bernard Lyot (1897--1952), lead him to inferred a coronal temperature as around 600,000 K.
1942- Solar radio emission: The solar radio emission, was contemplated earlier in 1890 by Thomas A. Edison (1847-1931), but first attempts were carried out by Sir Oliver Lodge (1851-1940). Difficulty of detecting the emission, because the strongest radio emission is associated with solar flares
1946- The solar ultraviolet spectrum: Difficulty of obtaining solar spectra shorter than 3000 Å, from ground is due to absorption by oxygen and ozone, the captured German V2-Rockets first used to overcome that.
Solar Physics: Time Line of Great Achievements
The following is a short background of Solar Physics timeline, and how we reached present developments, initiated by giants who lack proper tools, but insisted to achieve.
2- The Solar Flares Mechanism
2 Minutes Voiced Movie the 11 years Solar cycle!
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