what is the corona of the sun made of
Solar eclipse


until the advent of Arab and monastic observations in the early medieval period. The first recorded observation of the corona was made in Constantinople in AD 968. The first known telescopic observation of a total solar eclipse was made in France in 1706. Nine years later, English astronomer Edmund Halley accurately predicted and observed the solar eclipse of May 3, 1715. By the mid-19th century, scientific understanding of the Sun was improving through observations of the Sun's corona during solar eclipses. The corona was identified as part of the Sun's
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Corona


the Sun: the photosphere's average temperature is compared to the corona's one to three million kelvin. The corona is 10 times as dense as the photosphere, and so produces about one-millionth as much visible light. The corona is separated from the photosphere by the relatively shallow chromosphere. The exact mechanism by which the corona is heated is still the subject of some debate, but likely possibilities include induction by the Sun's magnetic field and magnetohydrodynamic waves from below. The outer edges of the Sun's corona are constantly
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Corona


A corona (meaning 'crown' in Latin derived from Ancient Greek 'κορώνη' (korōnè, “garland, wreath”)) 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. Spectroscopy measurements indicate strong ionization in the corona and a plasma temperature in excess of , much hotter than the surface of the Sun. Light from the corona comes
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WISPR


proximity to the Sun by taking coronagraph-style images of the solar corona and features like coronal streamers, plumes, and mass ejections. One of the goals is to better understand the structure of the solar corona near the Sun. WISPR is designed to study the electron density and velocity structure of the corona. The instrument field of view is planned to extend from 13 to 108 degrees away from the Sun, and does not directly image the Sun; the area of interest is a very wide field extending away from the Sun
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Corona


Sun, not to the Moon. In 1809, Spanish astronomer José Joaquín de Ferrer coined the term 'corona'. Based in his own observations of the 1806 solar eclipse at Kinderhook (New York), de Ferrer also proposed that the corona was part of the Sun and not of 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
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Coronal hole


Coronal holes are areas where the Sun's corona is colder, hence darker, and has lower-density plasma than average because there is lower energy and gas levels. Coronal holes are part of the Sun's corona and are constantly changing and reshaping because the corona is not uniform. The Sun contains magnetic fields that arch away from areas in the corona that are very thin due to the lower levels of energy and gas, which cause coronal holes to appear when they do not fall back. Thus, solar particles escape at
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Kappa Coronae Borealis


Kappa Coronae Borealis, Latinized from κ Coronae Borealis, is a star approximately 102 light years away in the constellation of Corona Borealis. The apparent magnitude is +4.82 (4.17 trillion times fainter than the Sun) and the absolute magnitude is +2.35 (9.82 times brighter than the Sun). It is an orange K-type subgiant star of spectral type K1IV, meaning it has nearly completely exhausted its hydrogen supply in its core. It is 1.32 times as massive as the Sun yet has brightened to 11.6 times its luminosity. Around
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Sun


the corona and solar wind is about 1,000,000–2,000,000 K; however, in the hottest regions it is 8,000,000–20,000,000 K. Although no complete theory yet exists to account for the temperature of the corona, at least some of its heat is known to be from magnetic reconnection. The corona is the extended atmosphere of the Sun, which has a volume much larger than the volume enclosed by the Sun's photosphere. A flow of plasma outward from the Sun into interplanetary space is the solar wind. The heliosphere, the tenuous outermost atmosphere of the
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Corona (satellite)


phased out, skilled technicians worried about their jobs would quit the program—leaving Corona without staff. The move to Sunnyvale ensured that enough skilled staff would be available.) The decisions regarding what to photograph were made by the Corona Target Program. Corona satellites were placed into near-polar orbits. This software, run by an on-board computer, was programmed to operate the cameras based on the intelligence targets to be imaged, the weather, the satellite's operational status, and what images the cameras had already captured
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Corona


been the complete absence, until the late 1990s, of any direct evidence of waves propagating through the solar corona. The first direct observation of waves propagating into and through the solar corona was made in 1997 with the Solar and Heliospheric Observatory space-borne solar observatory, the first platform capable of observing the Sun in the extreme ultraviolet (EUV) for long periods of time with stable photometry. Those were magneto-acoustic waves with a frequency of about 1 millihertz (mHz, corresponding to a wave period), that carry
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UW Coronae Borealis


UW Coronae Borealis, also known as MS 1603.6+2600, is a low-mass X-ray binary star system in the constellation Corona Borealis. Astronomer Simon Morris and colleagues discovered the X-ray source in 1990 and were able to match it up with a faint star with an average visual magnitude of 19.4. The system is thought to be made up of a neutron star that has an accretion disk that draws material from its companion, a star less massive than the Sun. The disk is asymmetrical. The variability
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Star


of super-heated plasma that can extend outward to several million kilometres. The existence of a corona appears to be dependent on a convective zone in the outer layers of the star. Despite its high temperature, and the corona emits very little light, due to its low gas density. The corona region of the Sun is normally only visible during a solar eclipse. From the corona, a stellar wind of plasma particles expands outward from the star, until it interacts with the interstellar medium. For the Sun, the influence
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Pi Coronae Borealis


Pi Coronae Borealis, Latinized from π Coronae Borealis, is a solitary, orange-hued star in the northern constellation of Corona Borealis. Its apparent magnitude is 5.58, which is bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 13.40 mas as measured from Earth, it is located about 243 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −5 km/s. It is most likely (98% chance) a member of
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Corona


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 features, which led some in the 19th century to suggest that it contained a previously unknown element, "coronium". Instead, these spectral features have since been
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Corona


being transported away due to open magnetic flux and hence generating the solar wind. The corona is not always evenly distributed across the surface of the sun. During periods of quiet, the corona is more or less confined to the equatorial regions, with coronal holes covering the polar regions. However, during the Sun's active periods, the corona is evenly distributed over the equatorial and polar regions, though it is most prominent in areas with sunspot activity. The solar cycle spans approximately 11 years, from solar minimum to the following
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Gamma Coronae Borealis


Gamma Coronae Borealis, Latinized from γ Coronae Borealis, is a binary star system in the northern constellation of Corona Borealis. It is visible to the naked eye with an apparent visual magnitude of 3.83. Based upon an annual parallax shift of 22.33 mas as seen from Earth, it is located about 146 light years from the Sun. The system is moving closer to the Sun with a radial velocity of about −15 km/s. The components of this system have been optically separated, with the secondary lying about one arc second
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Epsilon Coronae Borealis


Epsilon Coronae Borealis, Latinized from ε Coronae Borealis, is a multiple star system in the constellation Corona Borealis located around 230 light-years from the Solar System. It shines with a combined apparent magnitude of 4.13, meaning it is visible to the unaided eye in all night skies except those brightly lit in inner city locations. It is an orange giant around 1.7 times as massive as the Sun of spectral type K2III, which has exhausted its core fuel supply of hydrogen and swollen to 21 times the Sun's diameter and 151
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Alpha Coronae Borealis


peak activity level of the Sun. This higher activity level is expected for a young star of this class. The corona has a temperature of about 5 MK, which is much hotter than the Sun's corona. The upper limit of 14 km/s for the equatorial rotation velocity is equivalent to a rotation period of 3 days. More likely, the rotation period is 7–9 days. The space velocity components of this star system are U =, V = and W =. α CrB is believed to be a member
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Epsilon Eridani


convection zone. The X-ray luminosity of Epsilon Eridani is about (). It is more luminous in X-rays than the Sun at peak activity. The source for this strong X-ray emission is Epsilon Eridani's hot corona. Epsilon Eridani's corona appears larger and hotter than the Sun's, with a temperature of , measured from observation of the corona's ultraviolet and X-ray emission. The stellar wind emitted by Epsilon Eridani expands until it collides with the surrounding interstellar medium of diffuse gas and dust
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Weather


, the Sun's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind. Inconsistencies in this wind and larger events on the surface of the star, such as coronal mass ejections, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as space weather. Coronal mass ejections have been tracked as far out in the Solar System as
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S Coronae Australis


S Coronae Australis (S CrA), is a young binary star system estimated to be around 2 million years old located in the constellation Corona Australis. It is composed of a G-type main sequence star that is about as luminous as and just over twice as massive as the Sun, and a smaller K-type main sequence star that has around 50-60% of the Sun's luminosity and 1.3 times its mass. Both stars are T Tauri stars and both show evidence of having circumstellar disks. The system
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Corona


raising the temperature of the air surrounding it to something greater than its glass surface. Hence, some other manner of energy transfer must be involved in the heating of the corona. The amount of power required to heat the solar corona can easily be calculated as the difference between coronal radiative losses and heating by thermal conduction toward the chromosphere through the transition region. It is about 1 kilowatt for every square meter of surface area on the Sun's chromosphere, or 1/ of the amount of light energy that escapes the Sun. Many
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R Coronae Borealis


Borealis)". It has also been called a "reverse nova" because of its habit of fading from sight. The variable star designation R Coronae Borealis was introduced, as "Coronae R" by Friedrich Wilhelm Argelander in 1950. The variability of R Coronae Borealis was discovered by the English astronomer Edward Pigott in 1795. In 1935 it was the first star shown to have a different chemical composition than the sun via spectral analysis. R Coronae Borealis is the prototype of the R Coronae Borealis class of variable stars. It
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Corona Borealis


period of 3.45 days TY Coronae Borealis is a pulsating white dwarf (of ZZ Ceti) type, which is around 70% as massive as the Sun, yet has only 1.1% of its diameter. Discovered in 1990, UW Coronae Borealis is a low-mass X-ray binary system composed of a star less massive than the Sun and a neutron star surrounded by an accretion disk that draws material from the companion star. It varies in brightness in an unusually complex manner: the two stars orbit each other every 111
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Astrophysical X-ray source


, the presence of a very hot, tenuous gas surrounding the Sun was inferred indirectly from optical coronal lines of highly ionized species. In the mid-1940s radio observations revealed a radio corona around the Sun. After detecting X-ray photons from the Sun in the course of a rocket flight, T. Burnight wrote, "The sun is assumed to be the source of this radiation although radiation of wavelength shorter than 4 Å would not be expected from theoretical estimates of black body radiation from the solar corona." And, of course
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Theta Coronae Australis


Theta Coronae Australis, Latinized from θ Coronae Australis, is a star located in the constellation Corona Australis. Theta Coronae Australis is also known as HR 6951, and HD 170845. Parallax measurements by Hipparcos put it at a distance of roughly 560 light-years, or 171 parsecs, away from the Solar System. Theta Coronae Australis is a G-type giant star that is radiating 497 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,794 K. It has an apparent visual magnitude of 4.64, and
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Lambda Coronae Borealis


Lambda Coronae Borealis, Latinised from λ Coronae Borealis, is a star located in the constellation Corona Borealis, at a distance of . It is also known as HR 5936, and HD 142908. Lambda Coronae Borealis has been assigned a spectral class of F2 IV-V, meaning it is somewhat hotter than the sun and shows spectral features intermediate between a main sequence and subgiant star. It has an effective temperature of and radius of , making for a bolometric luminosity of . Lambda Coronae Borealis has an 11th magnitude companion star away
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Solar observation


as Glock attempted to connect variation in tree growth to periodic solar variations and infer long-term secular variability in the solar constant from similar variations in millennial-scale chronologies. Until the 1930s, little progress was made on understanding the Sun's corona, as it could only be viewed during infrequent total solar eclipses. Bernard Lyot's 1931 invention of the Coronagraph – a telescope with an attachment to block out the direct light of the solar disk – allowed the corona to be studied in full daylight. American astronomer George Ellery Hale
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Corona


waves carry energy from the solar interior to the solar chromosphere and corona. The Sun is made of plasma rather than ordinary gas, so it supports several types of waves analogous to sound waves in air. The most important types of wave are magneto-acoustic waves and Alfvén waves. Magneto-acoustic waves are sound waves that have been modified by the presence of a magnetic field, and Alfvén waves are similar to ultra low frequency radio waves that have been modified by interaction with matter in the plasma. Both types of waves
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Delta Coronae Borealis


Delta Coronae Borealis, Latinized from δ Coronae Borealis, is a variable star in the constellation Corona Borealis. Its apparent magnitude varies regularly between apparent magnitude 4.57 and 4.69, and it is around 170 light-years distant. δ Coronae Borealis is a yellow giant star of spectral type G3.5III that is around 2.4 times as massive as the Sun and has swollen to 7.4 times its radius. It has a surface temperature of 5180 K. For most of its existence, Delta Coronae Borealis was a blue-white main sequence star of spectral
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Sun


does not occur at a well-defined altitude. Rather, it forms a kind of nimbus around chromospheric features such as spicules and filaments, and is in constant, chaotic motion. The transition region is not easily visible from Earth's surface, but is readily observable from space by instruments sensitive to the extreme ultraviolet portion of the spectrum. The corona is the next layer of the Sun. The low corona, near the surface of the Sun, has a particle density around 10 m to 10 m. The average temperature of
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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
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Stellar wind


Sun have a wind driven by their hot, magnetized corona. The Sun's wind is called the solar wind. These winds consist mostly of high-energy electrons and protons (about 1 keV) that are able to escape the star's gravity because of the high temperature of the corona. Stellar winds from main-sequence stars do not strongly influence the evolution of lower mass stars such as the Sun. However, for more massive stars such as O stars, the mass loss can result in a star shedding as much
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FIELDS


FIELDS is a science instrument on the Parker Solar Probe (PSP), designed to measure magnetic fields in the solar corona during its mission to study the Sun. It is one of four major investigations on board PSP, along with WISPER, ISOIS, and SWEAP. It features three magnetometers. FIELDS is planned to help answer an enduring questions about the Sun, which is why is the solar corona is so hot compared to the surface of the Sun? and why is the solar wind so fast? (1 million miles
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Astrophotography


Fizeau. A failed attempt to obtain a photograph of a Total Eclipse of the Sun was made by the Italian physicist, Gian Alessandro Majocchi during an eclipse of the Sun that took place in his home city of Milan, on July 8, 1842. He later gave an account of his attempt and the Daguerreotype photographs he obtained, in which he wrote: The Sun's solar corona was first successfully imaged during the Solar eclipse of July 28, 1851. Dr. August Ludwig Busch, the Director of the Königsberg Observatory gave instructions
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Beta Coronae Borealis


Beta Coronae Borealis (β Coronae Borealis, abbreviated Beta CrB, β CrB) is a binary star in the constellation of Corona Borealis. It appears to the naked eye to be a single star and is the second-brightest star in its constellation with an apparent visual magnitude varying between 3.65 and 3.72. Based on parallax measurements taken during the Hipparcos mission, it is approximately 112 light-years from the Sun. The two components are designated Beta Coronae Borealis A (officially named Nusakan , the traditional name of the system)
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Gamma Coronae Australis


Gamma Coronae Australis (γ CrA), is a binary star located in the constellation Corona Australis. The system has a combined apparent visual magnitude of 4.20, making it faintly visible to the naked eye. It is located 56.4 light-years (17.3 parsecs) from the Sun, based on its parallax. Gamma Coronae Australis is a member of the Milky Way's thin disk. The system is a visual binary, where the orbit is calculated from observations of one star orbiting the other. The primary, Gamma Coronae Australis
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Corona Borealis


a surface temperature of 3033 K. One of the reddest stars in the sky, V Coronae Borealis is a cool star with a surface temperature of 2877 K that shines with a luminosity 102,831 times that of the Sun and is a remote 8810 light-years distant from Earth. Varying between magnitudes 6.9 and 12.6 over a period of 357 days, it is located near the junction of the border of Corona Borealis with Hercules and Bootes. Located 1.5° northeast of Tau Coronae Borealis, W Coronae Borealis ranges between magnitudes 7.8 and 14.3
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Alpha Coronae Borealis


Alpha Coronae Borealis (α Coronae Borealis, abbreviated Alpha CrB, α CrB), officially named Alphecca , is an eclipsing binary star in the constellation of Corona Borealis. It is located about 75 light years from the Sun and contains two main sequence stars, one class A and one class G. Alpha Coronae Borealis is a binary system, its stars orbiting each other in an eccentric orbit every 17.36 days. Because the plane of this orbit is inclined at an angle of 88.2° to the line of sight to the Earth,
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Kate & Kacey


made its debut on CMT on June 5, 2009. In January 2009, Kate & Kacey joined Little Big Town on tour as the group's opening act and hosted The Corona Sun City Tailgate Experience at several dates of Kenny Chesney's Sun City tour over the summer. The girls also made their "Grand Ole Opry" debut on May 8, 2009. Kate & Kacey grew up in Denver, Colorado, attended Cherry Creek High School, and later relocated to Nashville, Tennessee to pursue a career in country music.
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Solar eclipse of July 28, 1851


The earliest scientifically useful photograph of a total solar eclipse was made by Julius Berkowski at the Royal Observatory in Königsberg, Prussia, on Monday, July 28, 1851. It was the first correctly exposed photographic image taken during totality thereby including the Sun's corona. A solar eclipse occurs when the Moon passes between the Earth and the Sun, casting a shadow on Earth that temporarily obscures part or all of the Sun's disc. Eclipses can occur only when all three bodies are properly aligned. Partial eclipses, in which only
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Omicron Coronae Borealis


of K0 III. This indicates this is an evolved K-type giant star that has exhausted the hydrogen at its core and has left the main sequence. This is a red clump star, which means it is now generating energy through helium fusion at its core. It has 10% of the mass of the Sun and has expanded to over ten times the Sun's radius. The star is radiating 50 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,812 K. Omicron Coronae Borealis has one confirmed
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Omicron Coronae Borealis


Omicron Coronae Borealis, Latinized from o Coronae Borealis, is a star in the northern constellation of Corona Borealis. It is a faint star but visible to the naked eye on a dark night with an apparent visual magnitude of +5.53. The annual parallax shift of the star as seen from Earth is 12.08 mas, which provides a distance estimate of around 270 light years. It is moving closer to the Sun with a radial velocity of −54 km/s. Based upon the spectrum of this star, it has a stellar classification
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Rho Coronae Borealis


Rho Coronae Borealis (ρ CrB, ρ Coronae Borealis) is a Solar twin, yellow dwarf star approximately 57 light-years away in the constellation of Corona Borealis. The star is thought to be similar to the Sun with nearly the same mass, radius, and luminosity. In 1997, an extrasolar planet was announced on the basis of radial velocity measurements. This detection method gives only a minimum mass on the planet. Follow-up studies with the Hipparcos satellite indicate that the companion is actually low-mass star in
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Iota Coronae Borealis


Iota Coronae Borealis, Latinized from ι Coronae Borealis, is a binary star system in the constellation Corona Borealis. It is visible to the naked eye with a combined apparent visual magnitude of is 4.96. Based upon an annual parallax shift of 10.46 mas as seen from the Earth, it is located about 312 light years from the Sun. This is a single-lined spectroscopic binary with an orbital period of 35.5 days and an eccentricity of 0.56. The visible member, component A, has a stellar classification of , indicating it
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Corona


in raw sunlight; the F-corona extends to very high elongation angles from the Sun, where it is called the zodiacal light. The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma; it may be observed in broad or forbidden or hot spectral emission lines and is the main source of information about the corona's composition. In 1724, French-Italian astronomer Giacomo F. Maraldi recognized that the aura visible during a solar eclipse belongs to the
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Polarimeter to Unify the Corona and Heliosphere


Polarimeter to Unify the Corona and Heliosphere (PUNCH) is a planned mission by NASA to study the unexplored region from the middle of the solar corona out to 1 AU from the Sun. PUNCH will consist of a constellation of four microsatellites that through continuous 3D deep-field imaging, will observe the corona and heliosphere as elements of a single, connected system. The four microsatellites are planned to be launched no later than August 2022, along with a pair of secondary satellites named Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS
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X-ray astronomy


processes in the corona, which is its outer atmosphere. In the area of solar X-ray astronomy, there is the coronal heating problem. The photosphere of the Sun has an effective temperature of 5,570 K yet its corona has an average temperature of 1–2 × 10 K. However, the hottest regions are 8–20 × 10 K. The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere. It is thought that the energy necessary to heat the corona is provided by turbulent motion
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Zeta Coronae Australis


Zeta Coronae Australis (ζ Coronae Australis) is a solitary, blue-white hued star located in the southern constellation Corona Australis. With an apparent visual magnitude of +4.75, it is sufficiently bright to be viewed with the naked eye. Based upon an annual parallax shift of 16.89 mas as seen from Earth, this star is located around 193 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.15 due to interstellar dust. This is a B-type main sequence star with
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Mu Coronae Borealis


Mu Coronae Borealis, Latinized from μ Coronae Borealis, is a solitary, ruby-hued star located in the northern constellation of Corona Borealis. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.12. Based upon an annual parallax shift of 5.27 mas, it is located roughly 620 light years from the Sun. This is an evolved red giant star with a stellar classification of M1.5 IIIb. It is currently on the asymptotic giant branch and is a variable star of uncertain type, showing a change
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Corona Borealis


Coronae Borealis, a binary system that shines with a combined magnitude of 4.13 located 380±20 light-years distant. The brighter component, Theta Coronae Borealis A, is a blue-white star that spins extremely rapidly—at a rate of around 393 km per second. A Be star, it is surrounded by a debris disk. Flanking Alpha to the east is Gamma Coronae Borealis, yet another binary star system, whose components orbit each other every 92.94 years and are roughly as far apart from each other as the Sun and
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Corona Borealis


unrelated. The primary, Nu Coronae Borealis, is a red giant of spectral type M2III and magnitude 5.2, lying 640±30 light-years distant, and the secondary, Nu Coronae Borealis, is an orange-hued giant star of spectral type K5III and magnitude 5.4, estimated to be 590±30 light-years away. Sigma Coronae Borealis, on the other hand, is a true multiple star system divisible by small amateur telescopes. It is actually a complex system composed of two stars around as massive as the Sun that orbit each
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Nu2 Coronae Borealis


Nu Coronae Borealis is a solitary, orange-hued star located in the northern constellation of Corona Borealis. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.4. Based upon an annual parallax shift of 5.49 mas, it is located roughly 590 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.1 due to interstellar dust. This is an evolved red giant star with a stellar classification of K5 III. The measured angular diameter of Nu Coronae Borealis
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NIXT


The NIXT, or Normal Incidence X-ray Telescope, was a sounding rocket payload flown in the 1990s by Professor Leon Golub of the Smithsonian Astrophysical Observatory, to prototype normal-incidence (conventional) optical designs in extreme ultraviolet (EUV) solar imaging. In the EUV, the surface of the Sun appears dark, and hot structures in the solar corona appear bright; this allows study of the structure and dynamics of the solar corona near the surface of the Sun, which is not possible using visible light. NIXT and
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Loren Acton


involved in day-to-day operation and scientific utilization of satellite missions for studies of the Sun. Acton was a principal investigator for Soft X-ray Telescope (SXT) experiment on the Japan/US/UK Yohkoh mission The Yohkoh mission focused on the study of high-energy solar processes, such as solar flares, eruptions and the heating of the corona. The primary emission of the extremely hot outer atmosphere of the sun, the solar corona, is at X-ray wavelengths. The extended duration, high
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Sun


, which can be detected via their absorption spectra. The 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
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Iosif Shklovsky


a Postgraduate Course at the Astrophysics Department of the Sternberg State Astronomical Institute and remained working in the Institute until the end of his life. He died in Moscow, aged 68. He specialized in theoretical astrophysics and radio astronomy, as well as the Sun's corona, supernovae, and cosmic rays and their origins. He showed, in 1946, that the radio-wave radiation from the Sun emanates from the ionized layers of its corona, and he developed a mathematical method for discriminating between thermal and nonthermal radio waves in the
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Solar eclipse


Sun were not present, the Moon, illuminated by earthlight, would be easily visible from Earth. This would be essentially the same as the earthshine which can frequently be seen when the Moon's phase is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's photosphere, is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it. Artificial satellites can also pass in front of
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Extreme ultraviolet Imaging Telescope


a different colour of EUV light, and the wavelength to be observed is selected by a shutter that blocks light from all but the desired quadrant of the main telescope. The EIT wavelengths are of great interest to solar physicists because they are emitted by the very hot solar corona but not by the relatively cooler photosphere of the Sun; this reveals structures in the corona that would otherwise be obscured by the brightness of the Sun itself. EIT was originally conceived as a viewfinder instrument to help select observing targets for the other instruments on
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Solar wind


scale turbulent flow. In 2018, NASA launched the Parker Solar Probe, named in honor of Eugene Parker, on a mission to study the structure and dynamics of the solar corona, in an attempt to understand the mechanisms that cause particles to be heated and accelerated as solar wind. During its seven-year mission, the probe will make twenty-four orbits of the sun, passing further into the corona with each orbit's perihelion, ultimately passing within 0.04 astronomical units of the sun's surface. It is the first
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1874 Transit of Venus Expedition to Campbell Island


a view of Venus against the sun's corona – a view obscured by clouds at the moment of first contact. They also had a twenty-second view of Venus at the end of the transit between third and fourth contacts as it was half off the sun's disc. No useful measurements were able to be made. It took three weeks for the expedition to dismantle their camp and load the ship. They departed on 28 December. Although observations and measurements of the transit had been unsuccessful, Filhol published a comprehensive account
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Crab Nebula


, a phenomenon commonly seen in Wolf–Rayet stars. However, this would have created a shell around the nebula. Although attempts have been made at several wavelengths to observe a shell, none has yet been found. The Crab Nebula lies roughly 1.5 degrees away from the ecliptic—the plane of Earth's orbit around the Sun. This means that the Moon—and occasionally, planets—can transit or occult the nebula. Although the Sun does not transit the nebula, its corona passes in front of it. These
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Sigma Coronae Borealis


is a G-type main-sequence star like the Sun, and has similar parameters: a mass roughly equal to that of the Sun, and an effective temperature of 5950 K. A visual orbit has been calculated, with a period of about 730 years and a high eccentricity of 0.72. Sigma Corona Borealis itself is a close binary. Here, the two stars are extremely close and orbit fairly quickly, every 1.14 days. This tiny separation of only 0.0279 au has allowed the two stars to exert tidal forces on each
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Sigma Coronae Borealis


secondary is 9.0% more massive than the Sun, and both are 24.4% wider than the Sun. σ Coronae Borealis C, also known as HIP 79551, appears as a red dwarf with a spectral type of M2.5V. It too is a binary star, with a companion in a 52-year orbit. The companion has a mass of and has been detected through astrometry. The Washington Double Star Catalog (WDS), a compilation of observations of double stars, lists several components to the main system. Two of those are listed
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Coronal loop


Coronal loops are huge loops of magnetic field beginning and ending on the Sun's visible surface (photosphere) projecting into the solar atmosphere (corona). Hot glowing ionized gas (plasma) trapped in the loops makes them visible. Coronal loops range widely in size up to several thousand kilometers long. They are transient features of the solar surface, forming and dissipating over periods of seconds to days. They form the basic structure of the lower corona and transition region of the Sun. These highly structured loops are a direct consequence
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C/2011 W3 (Lovejoy)


corona, such as temperatures reaching more than one million kelvins and the exposure time of nearly an hour. However, the Solar Dynamics Observatory (SDO), as well as other Sun-monitoring spacecraft, observed the comet emerge from the corona intact. The STEREO and SOHO spacecraft continued to observe the comet as it moved away from the Sun. Before perihelion, the nucleus of Comet Lovejoy had been estimated to be between in diameter. Since the comet survived perihelion, it is thought that the nucleus must have been larger,
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Solar phenomena


Johnson Space Center; Langley Research Center, May 1999. Energetic protons can reach Earth within 30 minutes of a major flare's peak. A prominence is a large, bright, gaseous feature extending outward from the Sun's 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
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Rho Coronae Borealis


a nearly face-on orbit. Rho Coronae Borealis is a solar analog, yellow dwarf star of the spectral type "G0-2Va". The star is thought to have only 95 percent of the Sun's mass, along with 1.31 times its radius and 1.61 of its luminosity. It may only be 51 to 65 percent as enriched with elements heavier than hydrogen (based on its abundance of iron) and may be somewhat older than the Sun at around six billion years old. A companion, initially thought to be
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Small-angle X-ray scattering


of the sample. The major problem that must be overcome in SAXS instrumentation is the separation of the weak scattered intensity from the strong main beam. The smaller the desired angle, the more difficult this becomes. The problem is comparable to one encountered when trying to observe a weakly radiant object close to the sun, like the sun's corona. Only if the moon blocks out the main light source does the corona become visible. Likewise, in SAXS the non-scattered beam that merely travels through the sample must be blocked
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Alfvén wave


see a decrease in temperature when moving away from a heat source, but this does not seem to be the case even though the photosphere is denser and would generate more heat than the corona. In 1942, Hannes Alfvén proposed in "Nature" the existence of an electromagnetic-hydrodynamic wave which would carry energy from the photosphere to heat up the corona and the solar wind. He claimed that the sun had all the necessary criteria to support these waves and they may in turn be responsible for sun spots. He quotes:
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Proxima Centauri


Sun even at the peak of the solar cycle. Even during quiescent periods with few or no flares, this activity increases the corona temperature of Proxima Centauri to 3.5 million K, compared to the 2 million K of the Sun's corona. Proxima Centauri's overall activity level is considered low compared to other red dwarfs, which is consistent with the star's estimated age of 4.85 years, since the activity level of a red dwarf is expected to steadily wane over billions of years as its stellar rotation rate decreases. The activity
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Corona Australis


the Sun. Beta Coronae Australis is an orange giant 474 light years from Earth. Its spectral type is K0II, and it is of apparent magnitude 4.11. Since its formation, it has evolved from a B-type star to a K-type star. Its luminosity class places it as a bright giant; its luminosity is 730 times that of the Sun, designating it one of the highest-luminosity K0-type stars visible to the naked eye. 100 million years old, it has a radius of 43 solar radii (
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SWAP (instrument)


The "Sun Watcher using Active Pixel System Detector and Image Processing" (SWAP) telescope is a compact EUV imager on board the PROBA2 mission that will observe the Sun in extreme ultraviolet (EUV). SWAP will provide images of the solar corona at a temperature of roughly 1 million degrees. This instrument was built upon the heritage of the Extreme ultraviolet Imaging Telescope (EIT) which monitors the solar corona since 1996. SWAP will continue the systematic CME (coronal mass ejection) watch program at an improved image cadence (typically
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Solar wind


The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. Embedded within the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a
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Coronal seismology


Coronal seismology is a technique of studying the plasma of the Sun's corona with the use of magnetohydrodynamic (MHD) waves and oscillations. Magnetohydrodynamics studies the dynamics of electrically conducting fluids - in this case the fluid is the coronal plasma. Observed properties of the waves (e.g. period, wavelength, amplitude, temporal and spatial signatures (what is the shape of the wave perturbation?), characteristic scenarios of the wave evolution (is the wave damped?), combined with a theoretical modelling of the wave phenomena (dispersion relations
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Coronal radiative losses


In astronomy and in astrophysics, for radiative losses of the solar corona, it is meant the energy flux radiated from the external atmosphere of the Sun (traditionally divided into chromosphere, transition region and corona), and, in particular, the processes of production of the radiation coming from the solar corona and transition region, where the plasma is optically-thin. On the contrary, in the chromosphere, where the temperature decreases from the photospheric value of 6000 K to the minimum of 4400 K, the optical depth is about
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High Resolution Coronal Imager


The High Resolution Coronal Imager (Hi-C) is a sub-orbital telescope designed to take high-resolution images of the Sun's corona. It was launched on July 11, 2012 aboard a Black Brant sounding rocket from White Sands Missile Range, New Mexico. The images taken were the highest resolution photos ever of the Sun's corona. The telescope weighs , and is long. The mirrors are approximately across. Its optics were designed at the Marshall Space Flight Center in Huntsville, Alabama with assistance from the Smithsonian
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X-ray astronomy


species. The Sun has been known to be surrounded by a hot tenuous corona. In the mid-1940s radio observations revealed a radio corona around the Sun. The beginning of the search for X-ray sources from above the Earth's atmosphere was on August 5, 1948 12:07 GMT. A US Army (formerly German) V-2 rocket as part of Project Hermes was launched from White Sands Proving Grounds. The first solar X-rays were recorded by T. Burnight. Through the 1960s, 70s, 80s, and 90s, the
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Corona


minimum. Since the solar magnetic field is continually wound up due to the faster rotation of mass at the sun's equator (differential rotation), sunspot activity will be more pronounced at solar maximum where the magnetic field is more twisted. Associated with sunspots are coronal loops, loops of magnetic flux, upwelling from the solar interior. The magnetic flux pushes the hotter photosphere aside, exposing the cooler plasma below, thus creating the relatively dark sun spots. Since the corona has been photographed at high resolution in the X-ray
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Owens Valley Solar Array


, the release of magnetic energy in the corona, and the space weather consequences of solar activity. The array employs its seven antennas to perform radio interferometry at up to 86 radio frequencies ranging from 1 to 18 gigahertz (microwave range). The combination of spatial and spectral resolution is called microwave imaging spectroscopy, which provides rich diagnostic information about the Sun. It is sensitive to both thermal radiation from the chromosphere and corona of the Sun, and to non-thermal radiation from high-energy electrons accelerated in solar flares.
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Solar eclipse


, as well as telescopes. A total solar eclipse provides a rare opportunity to observe the corona (the outer layer of the Sun's atmosphere). Normally this is not visible because the photosphere is much brighter than the corona. According to the point reached in the solar cycle, the corona may appear small and symmetric, or large and fuzzy. It is very hard to predict this in advance. As the light filters through leaves of trees during a partial eclipse, the overlapping leaves create natural pinholes, displaying mini eclipses
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House System at the California Institute of Technology


the corona of the sun as a metaphor for the outer reaches of Lloyd). The Place used to exist on the corner of Michigan Ave and Lura St; it was removed around 1988 and is now a parking lot. Corona used to be on the east side of Holliston Ave; it was removed in 1992 and the location is now the new parking structure. Because of Pasadena preservation laws, both houses were moved to other places in Pasadena. The Corona house was donated to a minister (for free) who restored
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Corona Borealis


days at an average distance of around 1.3 AU. Epsilon itself is a orange giant of spectral type K2III that has swollen to and . Kappa Coronae Borealis is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lie a dust debris disk, and one planet with a period of 3.4 years. This planet's mass is estimated at . The dimensions of the debris disk indicate it is likely there is a second substellar companion. Omicron Coronae Borealis is a K-type clump giant with one confirmed
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Nu1 Coronae Borealis


Nu Coronae Borealis is a solitary, red-hued star located in the constellation Corona Borealis. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.20. Based upon an annual parallax shift of 5.09 mas, it is located roughly 640 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.1 due to interstellar dust. This is an evolved red giant star with a stellar classification of M2 III. It is a variable star of uncertain type, showing
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Corona


ray telescopes. Some stellar coronae, particularly in young stars, are much more luminous than the Sun's. For example, FK Comae Berenices is the prototype for the FK Com class of variable star. These are giants of spectral types G and K with an unusually rapid rotation and signs of extreme activity. Their X-ray coronae are among the most luminous ("L" ≥ 10 erg·s or 10W) and the hottest known with dominant temperatures up to 40 MK. The astronomical observations planned with the Einstein Observatory by
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STS-87


designed to perform remote sensing of the hot outer layers of the sun's atmosphere or corona. It is expected to be deployed on orbit 18 and retrieved on orbit 52. The objective of the observations are to investigate the mechanisms causing the heating of the solar corona and the acceleration of the solar wind which originates in the corona. Two primary experiments are the Ultraviolet Coronal Spectrometer from the Smithsonian Astrophysical Observatory, and the White Light Coronograph (WLC) from the High Altitude Observatory. Spartan 201 has three secondary experiments. The Technology
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Giacomo F. Maraldi


famous astronomical discovery was that the ice caps on Mars are not exactly on the rotational poles of that body. He also recognized (in May 1724) that the corona visible during a solar eclipse belongs to the Sun not to the Moon, and he discovered R Hydrae as a variable star. He also helped with the survey based on the Paris Meridian. He is also credited for the first observation (1723) of what is usually referred to as Poisson's spot, an observation that was unrecognized until its rediscovery in the
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Thor (film)


would work in stereo. In the film, Odin enters what is known as the "Odinsleep" in his chamber to regenerate. Butterworth stated, "For Odin's Chamber, we developed a dome and curtain of light rays that hover over Odin's bed. This dome of light suggests harnessed power and energy that revitalizes him as he sleeps. We took a lot of reference from the natural world such as the corona of the sun and gave the sleep effect plenty of volume and space". The film's score was
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Ascendant Sun


Ascendant Sun is a novel which tells the story of how Kelric made it back to Earth, to become Imperator of the Skolian Empire and lead his people towards peace with the Eubians in the Saga of the Skolian Empire series by Catherine Asaro. The book begins just after Kelric has escaped the planet of Coba, where he had been held prisoner for over 18 years. Forced to land because of his ships short fuel supply, Kelric takes up a lucrative job as the spaceship Corona's tactical officer under the command of Jafe Maccar
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Theta Coronae Borealis


stars, recognizable because the gas radiates emission lines that give a characteristic pattern in the star's spectrum. Of spectral type B6Vnn, Theta Coronae Borealis A is around six times as massive as the Sun and has four times the diameter. It has a surface temperature of around 14910 K. In 1970, it faded by 0.7 magnitude, becoming 50% fainter. The cause for this is unknown, but thought possibly due to ejection of dust that obscured the star's light. Theta Coronae Borealis B is a white main sequence star
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Xi Coronae Borealis


Xi Coronae Borealis (ξ CrB) is a binary star system in the northern constellation of Corona Borealis. It is visible to the naked eye with a combined apparent visual magnitude of 4.85. Based upon an annual parallax shift of 17.78 mas as seen from the Earth, it is located about 183 light years from the Sun. As of 2009, the pair had an angular separation of 91 mas along a position angle of 139.4°. The brighter member, component Aa, is an evolved K-type giant star with a
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Crab Nebula


the variations in the nebula's brightness can be used to create maps of X-ray emission. When X-rays were first observed from the Crab Nebula, a lunar occultation was used to determine the exact location of their source. The Sun's corona passes in front of the Crab Nebula every June. Variations in the radio waves received from the Crab Nebula at this time can be used to infer details about the corona's density and structure. Early observations established that the corona extended out to much greater distances than had
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Sun


6,000 K, whereas the temperature of the corona reaches 1,000,000–2,000,000 K. The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere. It is thought that the energy necessary to heat the corona is provided by turbulent motion in the convection zone below the photosphere, and two main mechanisms have been proposed to explain coronal heating. The first is wave heating, in which sound, gravitational or magnetohydrodynamic waves are produced by turbulence in the convection zone. These waves travel upward and dissipate in
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Sun


the corona, depositing their energy in the ambient matter in the form of heat. The other is magnetic heating, in which magnetic energy is continuously built up by photospheric motion and released through magnetic reconnection in the form of large solar flares and myriad similar but smaller events—nanoflares. Currently, it is unclear whether waves are an efficient heating mechanism. All waves except Alfvén waves have been found to dissipate or refract before reaching the corona. In addition, Alfvén waves do not easily dissipate in the corona. Current research focus
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Corona


active solar corona to temperatures of up to 4 million kelvin. The main heat source in the quiescent corona (about 1.5 million kelvin) is assumed to originate from MHD waves. The NASA mission Parker Solar Probe is intended to approach the Sun to a distance of approximately 9.5 solar radii to investigate coronal heating and the origin of the solar wind. It has been successfully launched on August 12, 2018 and is currently leaving Earth for the first orbit. The wave heating theory, proposed in 1949 by Evry Schatzman, proposes that
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Our Mr. Sun


the gas at the center is more than 100 times heavier than water with a pressure of one billion tons per square inch while the surface is about one pound per square inch. The center is 30 million degrees Fahrenheit while the surface is only 10,000 degrees, but the corona is 1 million degrees Fahrenheit though nobody knows why, so scientists study the corona during each solar eclipse. Dr. George Ellery Hale and Dr. Henri Deslandres both developed the spectroheliograph—independently—to study the Sun in different wavelengths of light related to specific atoms
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Seth Barnes Nicholson


on sunspot activity. He also made a number of eclipse expeditions to measure the brightness and temperature of the Sun's corona. In the early 1920s, he and Edison Pettit made the first systematic infrared observations of celestial objects. They used a vacuum thermocouple to measure the infrared radiation and thus the temperature of the Moon which led to the theory that the Moon was covered with a thin layer of dust acting as an insulator, and also of the planets, sunspots and stars. Their temperatures measurements of nearby giant stars led to
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Funny Pets


Funny Pets () is a Japanese digital computer (CGI) anime series created and directed by Ryuji Masuda that was made in 2006. The sound effects were made by Shizuo Kurahashi. The plot of the series is that a UFO carrying two aliens from another planet ends up falling into Earth, where they are saved by a moody air-headed showgirl called Funny. The two aliens, the moon-like Crescent and the sun-like Corona, must adjust to life as Funny's pets. There are 24 episodes in
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Corona Borealis


Jupiter. Possible stable planetary orbits in the habitable zone were calculated for the binary star Eta Coronae Borealis, which is composed of two stars—yellow main sequence stars of spectral type G1V and G3V respectively—similar in mass and spectrum to the Sun. No planet has been found, but a brown dwarf companion about 63 times as massive as Jupiter with a spectral type of L8 was discovered at a distance of 3640 AU from the pair in 2001. Corona Borealis contains few galaxies observable with amateur telescopes. NGC 6085 and 6086
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Corona


Giuseppe Vaiana and his group showed that F-, G-, K- and M-stars have chromospheres and often coronae much like our Sun. The "O-B stars", which do not have surface convection zones, have a strong X-ray emission. However these stars do not have coronae, but the outer stellar envelopes emit this radiation during shocks due to thermal instabilities in rapidly moving gas blobs. Also A-stars do not have convection zones but they do not emit at the UV and X-ray wavelengths
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