"chromosphere, transition region, and corona are much hotter than the surface of the Sun. The reason is not well understood, but evidence suggests that Alfvén waves may have enough energy to heat the corona. Above the temperature minimum layer is a layer about thick, dominated by a spectrum of emission and absorption lines. It is called the ""chromosphere"" from the Greek root ""chroma"", meaning color, because the chromosphere is visible as a colored flash at the beginning and end of total solar eclipses. The temperature of the chromosphere increases gradually with altitude, ranging up to around near the top. In"
"individual small water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface. The aureole is often (especially in case of the Moon) the only visible part of the corona and has the appearance of a bluish-white disk which fades to reddish-brown towards the edge. Aureola An aureola or aureole (diminutive of Latin ""aurea"", ""golden"") is the radiance of luminous cloud which, in paintings of sacred personages, surrounds the whole figure. In Neolatin languages (as Italian, Spanish, Portuguese and French) the noun Aureola is usually more related to the disc of light surrounding the head"
"has steadily increased in luminosity by 40% since it first became a main-sequence star. The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth. The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages. The visible outer surface of the Sun is called the photosphere. Above this layer is a thin region known as the chromosphere. This is surrounded by a transition region of rapidly increasing temperatures, and finally by the super-heated corona. At the center of the Sun is the core region,"
"Aureola An aureola or aureole (diminutive of Latin ""aurea"", ""golden"") is the radiance of luminous cloud which, in paintings of sacred personages, surrounds the whole figure. In Neolatin languages (as Italian, Spanish, Portuguese and French) the noun Aureola is usually more related to the disc of light surrounding the head of sacred figures and that in English is called Halo or Nimbus. In the earliest periods of Christian art it was confined to the figures of the persons of the Christian Godhead, but it was afterwards extended to the Virgin Mary and to several of the saints. The aureola, when"
"but more tenuous corona. Other ""surface features"" on the photosphere are solar flares and sunspots. Photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/""phos, photos"" meaning ""light"" and σφαῖρα/""sphaira"" meaning ""sphere"", in reference to it being a spherical surface that is perceived to emit light. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately 2/3, or equivalently, a depth from which 50% of light will escape without being scattered. In other words, a photosphere is the"
"the Moon. English astronomer Norman Lockyer identified the first element unknown on Earth in the Sun's chromosphere, which was called helium. French astronomer Jules Jenssen noted that the size and shape of the corona changes with the sunspot cycle. In 1930, Bernard Lyot invented the coronograph, which allows to see the corona without a total eclipse. In 1952, American astronomer Eugene Parker proposed that the solar corona might be heated by myriad tiny 'nanoflares', miniature brightenings resembling solar flares that would occur all over the surface of the Sun. The high temperature of the Sun's corona gives it unusual spectral"
"Corona A corona (Latin, 'crown') is an aura of plasma that surrounds the Sun and other stars. The Sun's corona extends millions of kilometres into outer space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph. The word ""corona"" is a Latin word meaning ""crown"", from the Ancient Greek κορώνη (korōnè, “garland, wreath”). Spectroscopy measurements indicate strong ionization and plasma temperature in excess of 1,000,000 kelvins, much hotter than the surface of the Sun. Light from the corona comes from three primary sources, from the same volume of space. The K-corona"
"see is produced as electrons react with hydrogen atoms to produce H ions. The photosphere is tens to hundreds of kilometers thick, and is slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or ""limb"" of the solar disk, in a phenomenon known as limb darkening. The spectrum of sunlight has approximately the spectrum of a black-body radiating at 5,777 K, interspersed with atomic absorption lines from the tenuous layers above the photosphere. The photosphere"
"temporal resolutions of the newer instruments reveal this coronal mass supply. These observations reveal a one-to-one connection between plasma that is heated to millions of degrees and the spicules that insert this plasma into the corona. Corona A corona (Latin, 'crown') is an aura of plasma that surrounds the Sun and other stars. The Sun's corona extends millions of kilometres into outer space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph. The word ""corona"" is a Latin word meaning ""crown"", from the Ancient Greek κορώνη (korōnè, “garland, wreath”). Spectroscopy measurements"
"Corona (optical phenomenon) In meteorology, a corona (plural ""coronae"") is an optical phenomenon produced by the diffraction of sunlight or moonlight (or, occasionally, bright starlight or planetlight) by individual small water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface. In its full form, a corona consists of several concentric, pastel-colored rings around the celestial object and a central bright area called ""aureole"". The aureole is often (especially in case of the Moon) the only visible part of the corona and has the appearance of a bluish-white disk which fades to reddish-brown towards the"
"Solar prominence A prominence is a large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. The prominence plasma is typically a hundred times more luminous and denser than the coronal plasma. A prominence forms over timescales of about a day and may persist in the"
"the symbol ""au"". In the 2014 revision of the SI Brochure, the BIPM used the unit symbol ""au"". Earth's orbit around the Sun is an ellipse. The semi-major axis of this elliptic orbit is defined to be half of the straight line segment that joins the perihelion and aphelion. The centre of the Sun lies on this straight line segment, but not at its midpoint. Because ellipses are well-understood shapes, measuring the points of its extremes defined the exact shape mathematically, and made possible calculations for the entire orbit as well as predictions based on observation. In addition, it mapped"
"30,000 kilometers in diameter with lifespans of up to 24 hours. Granule (solar physics) Granules on the photosphere of the Sun are caused by convection currents (thermal columns, Bénard cells) of plasma within the Sun's convective zone. The grainy appearance of the solar photosphere is produced by the tops of these convective cells and is called ""granulation"". The rising part of the granules is located in the center where the plasma is hotter. The outer edge of the granules is darker due to the cooler descending plasma. (The terms ""darker"" and ""cooler"" are strictly by comparison to the brighter, hotter"
"unmapped. There are also ongoing studies of the region between Mercury and the Sun. Objects may yet be discovered in the Solar System's uncharted regions. Currently, the furthest known objects, such as Comet West, have aphelia around 70,000 AU from the Sun, but as the Oort cloud becomes better known, this may change. The Solar System is located in the Milky Way, a barred spiral galaxy with a diameter of about 100,000 light-years containing about 100 billion stars. The Sun resides in one of the Milky Way's outer spiral arms, known as the Orion–Cygnus Arm or Local Spur. The Sun"
"from the sun and it is possibly due to a fragmentation of the comet nucleus. An alternative explanation is that the brightness peak at 12 solar radii comes from the sublimation of amorphous olivines and the peak at 11.2 solar radii is from the sublimation of crystalline olivines. The peak at 7 solar radii could then be the sublimation of pyroxene. The most famous sungrazers are the Kreutz Sungrazers, which all originate from one giant comet that broke up into many smaller comets during its first passage through the inner Solar System. An extremely bright comet seen by Aristotle and"
"surface, often in the shape of a loop. Prominences are anchored to the Sun's surface in the photosphere and extend outwards into the corona. While the corona consists of high temperature plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. Prominence plasma is typically a hundred times cooler and denser than coronal plasma. A prominence forms over timescales of about an earthly day and may persist for weeks or months. Some prominences break apart and from CMEs. A typical prominence extends over many thousands of kilometers; the largest"
"gathered in the center, while the rest flattened into an orbiting disk that became the balance of the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. The Sun is a G-type main-sequence star (G2V) based on spectral class and it is informally designated as a ""yellow dwarf"" because its visible radiation is most intense in the yellow-green portion of the spectrum. It is actually white, but from the Earth's surface it appears yellow because of atmospheric scattering of blue light. In the spectral class label, ""G2"" indicates its surface temperature, of"
"to eclipse. Different versions of Eclipse have been given different science-related names. The versions named after Callisto, Europa, and Ganymede, which are moons of Jupiter, were followed by a version named after Galileo the discoverer of those moons. These were followed by two sun-themed names, Helios of Greek mythology, and Indigo, one of the seven colors of a rainbow (which is produced by the sun). The version after that, Juno, has a triple meaning: a Roman mythological figure, an asteroid, and a spacecraft to Jupiter. Kepler, Luna, and Mars continued the astronomy theme, and then Neon and Oxygen constitutes a"
"1800s, from which properties of the solar atmosphere could be determined, while the creation of daguerreotypy led to the first solar photographs on 2 April 1845. Photography assisted in the study of solar prominences, granulation and spectroscopy. Early in the 20th century, interest in astrophysics surged in America. A number of new observatories were built with solar telescopes around the world. The 1931 invention of the coronagraph allowed the corona to be studied in full daylight. The Sun is a star located at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma and"
"Chlorophane Chlorophane, also sometimes known as pyroemerald, cobra stone, and pyrosmaragd, is a rare variety of the mineral fluorite with the unusual combined properties of thermoluminescence, thermophosphoresence, triboluminescence, and fluorescence: it will emit light in the visible spectrum when exposed to ultraviolet light, when heated, and when rubbed; if heated, it will continue to emit light for a period of time after a heat source is withdrawn. The small amount of heat generated by being held in the hand has been reported as enough to induce luminiscence, though this may be the result of experimental error. Although chemically very similar"
"the Baily’s beads disappear behind the advancing lunar edge (the beads also reappear at the end of totality), a thin reddish edge called the chromosphere (the Greek ""chromos"" meaning ""color"") appears. Though the reddish hydrogen radiation is most visible to the unaided eye, the chromosphere also emits thousands of additional spectral lines. Although Baily is often said to have discovered the cause of the feature which bears his name, Sir Edmond Halley made the first recorded observations of Baily's beads during the solar eclipse of 3 May 1715. Halley described and correctly ascertained the cause of the effect in his"
"Chrysoprase Chrysoprase, chrysophrase or chrysoprasus is a gemstone variety of chalcedony (a cryptocrystalline form of silica) that contains small quantities of nickel. Its color is normally apple-green, but varies to deep green. The darker varieties of chrysoprase are also referred to as prase. (However, the term prase is also used to describe chlorite-included quartz, and to a certain extent is a color-descriptor, rather than a rigorously defined mineral variety.) Chrysoprase is cryptocrystalline, which means that it is composed of crystals so fine that they cannot be seen as distinct particles under normal magnification. This sets it apart from rock crystal,"
"enveloping the whole body, generally appears oval or elliptical in form, but occasionally depicted as circular, vesica piscis, or quatrefoil. When it appears merely as a luminous disk round the head, it is called specifically a ""halo"" or ""nimbus"", while the combination of nimbus and aureole is called a ""glory"". The strict distinction between nimbus and aureole is not commonly maintained, and the latter term is most frequently used to denote the radiance round the heads of saints, angels or Persons of the Trinity. This is not to be confused with the specific ""motif"" in art of the Infant Jesus"
"(0.2%), and iron (0.2%) being the most abundant. The Sun's photosphere has a temperature between (with an effective temperature of ) and a density somewhere around 1 to 1 kg/m; other stars may have hotter or cooler photospheres. The Sun's photosphere is around 100 kilometers thick, and is composed of convection cells called granules—cells of plasma each approximately 1000 kilometers in diameter with hot rising plasma in the center and cooler plasma falling in the narrow spaces between them, flowing at velocities of 7 kilometer per second. Each granule has a lifespan of only about twenty minutes, resulting in a"
"sunspots and faculae, occur in the photosphere, spicules, Hα filaments and plages in the chromosphere, prominences in the chromosphere and transition region, and flares and coronal mass ejections happen in the corona and chromosphere. If flares are very violent, they can also perturb the photosphere and generate a Moreton wave. On the contrary, quiescent prominences are large, cool dense structures which are observed as dark, ""snake-like"" Hα ribbons (appearing like filaments) on the solar disc. Their temperature is about 5000–8000 K, and so they are usually considered as chromospheric features. In 2013, images from the High Resolution Coronal Imager revealed"
"mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally and not completely accurately referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot"
"certain wavelengths. The surface of a star is defined to have a temperature given by the effective temperature in the Stefan–Boltzmann law. Stars, except neutron stars, have no solid surface. Therefore, the photosphere is typically used to describe the Sun's or another star's visual surface . The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon"
"Circumscribed halo A circumscribed halo is a type of halo, an optical phenomenon typically in the form of a more or less oval ring that circumscribes the circular 22° halo centred on the sun or moon. As the sun rises above 70° it essentially covers the 22° halo. Like many other halos, it is slightly reddish on the inner edge, facing the sun or moon, and bluish on the outer edge. The shape of the circumscribed halo is strongly dependent on the distance of the sun or moon above the horizon. Its top and bottom (i.e., the points directly below"
"Photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/""phos, photos"" meaning ""light"" and σφαῖρα/""sphaira"" meaning ""sphere"", in reference to it being a spherical surface that is perceived to emit light. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately 2/3, or equivalently, a depth from which 50% of light will escape without being scattered. In other words, a photosphere is the deepest region of a luminous object, usually a star, that is transparent to photons of"
"The luminosity stays approximately constant as the temperature increases, with the ejected half of the Sun's mass becoming ionised into a planetary nebula as the exposed core reaches 30,000 K. The final naked core, a white dwarf, will have a temperature of over 100,000 K, and contain an estimated 54.05% of the Sun's present day mass. The planetary nebula will disperse in about 10,000 years, but the white dwarf will survive for trillions of years before fading to a hypothetical black dwarf. The Sun lies close to the inner rim of the Milky Way's Orion Arm, in the Local Interstellar"
"Capella Capella, also designated Alpha Aurigae (α Aurigae, abbreviated Alpha Aur, α Aur), is the brightest point of light in the constellation of Auriga, the sixth-brightest in the night sky, and the third-brightest in the northern celestial hemisphere after Arcturus and Vega. A prominent object in the winter sky of the northern hemisphere, it is circumpolar to observers north of 44°N. Its name meaning ""little goat"" in Latin, Capella depicted the goat Amalthea that suckled Zeus in classical mythology. The Capella system is relatively close, at only from the Sun. Although it appears to be a single star to the"
"Orion Arm The Orion Arm is a minor spiral arm of the Milky Way some across and approximately in length, containing the Solar System, including the Earth. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur. The arm is named for the Orion constellation, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of the constellation (e.g. Betelgeuse, Rigel, the three stars of Orion's Belt, the"
"seal, is the terrestrial globe with the sun's eight-rayed corona extending behind it. The sun represents the dissemination of truth and knowledge as light. The eight-rayed sun represents the various branches into which general education at the time was divided, and the arrangement of the rays ""stood for the unity and democracy of the various branches of learning"" Encompassing the globe is a band with the Greek letters Phi(Φ) Kappa(K) Phi(Φ), representing the honor society's motto, (""Philosophía Krateítõ Phõtôn""). This band represents the bond of fellowship that binds all lovers of learning in a common purpose. The Seal of the"