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38-461: This nebula was discovered by the French astronomer Charles Messier while searching for comets in late January 1779. Messier's report of his independent discovery of Comet Bode reached fellow French astronomer Antoine Darquier de Pellepoix two weeks later, who then independently rediscovered the nebula while following the comet. Darquier later reported that it was "...as large as Jupiter and resembles

76-423: A list of them , in collaboration with his friend and assistant Pierre Méchain (who may have found at least 20 of the objects ), to avoid wasting time sorting them out from the comets they were looking for. The entries are now known to be 39  galaxies , 4  planetary nebulae , 7 other types of nebulae , 26  open star clusters and 29  globular star clusters . Messier did his observing with

114-493: A 100 mm (four-inch) refracting telescope from Hôtel de Cluny (now the Musée national du Moyen Âge ), in downtown Paris , France. The list he compiled only contains objects found in the area of the sky Messier could observe, from the north celestial pole to a declination of about −35.7° . They are not organized scientifically by object type, or by location. The first version of Messier's catalogue contained 45 objects and

152-478: A ; therefore, e may again be identified as the eccentricity . (See ellipse .) These formulas are identical in the sense that the formula for S oblate can be used to calculate the surface area of a prolate spheroid and vice versa. However, e then becomes imaginary and can no longer directly be identified with the eccentricity. Both of these results may be cast into many other forms using standard mathematical identities and relations between parameters of

190-537: A compact white dwarf star. The central star now consists primarily of carbon and oxygen with a thin outer envelope composed of lighter elements. Its mass is about 0.61–0.62  M ☉ , with a surface temperature of 125,000 ± 5,000  K . Currently it is 200 times more luminous than the Sun , but its apparent magnitude is only +15.75. Charles Messier Charles Messier ( French: [ʃaʁl me.sje] ; 26 June 1730 – 12 April 1817)

228-506: A few darker zones on the eastern and western edges of the ring and some faint nebulosity inside the disk. The central star , at magnitude 14.8, is difficult to spot. M57 is 0.787  kpc (2,570 light-years ) from Earth . It has a visual magnitude of 8.8 and a dimmer photographic magnitude , of 9.7. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1  arcsecond per century, which corresponds to spectroscopic observations as 20– 30 km/s . M57

266-404: A massive body in a close orbit. The most extreme example is Jupiter's moon Io , which becomes slightly more or less prolate in its orbit due to a slight eccentricity, causing intense volcanism . The major axis of the prolate spheroid does not run through the satellite's poles in this case, but through the two points on its equator directly facing toward and away from the primary. This combines with

304-419: A planet which is fading" (which may have contributed to the use of the persistent "planetary nebula" terminology). It would be entered into Messier's catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope. In 1800, German Count Friedrich von Hahn announced that he had discovered

342-456: A sphere. An oblate spheroid with c < a has surface area The oblate spheroid is generated by rotation about the z -axis of an ellipse with semi-major axis a and semi-minor axis c , therefore e may be identified as the eccentricity . (See ellipse .) A prolate spheroid with c > a has surface area The prolate spheroid is generated by rotation about the z -axis of an ellipse with semi-major axis c and semi-minor axis

380-404: A tri-axial ellipsoid centred at the origin with semi-axes a , b and c aligned along the coordinate axes is The equation of a spheroid with z as the symmetry axis is given by setting a = b : The semi-axis a is the equatorial radius of the spheroid, and c is the distance from centre to pole along the symmetry axis. There are two possible cases: The case of a = c reduces to

418-409: Is best observed using a telescope with an aperture of at least 20 cm (8 in), but even a 7.5 cm (3 in) telescope will reveal its elliptical ring shape. Using a UHC or OIII filter greatly enhances visual observation, particularly in light polluted areas. The interior hole can be resolved by a 10 cm (4 in) instrument at a magnification of 100×. Larger instruments will show

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456-404: Is illuminated by a central white dwarf of 15.75v visual magnitude . All the interior parts of this nebula have a blue-green tinge that is caused by the doubly ionized oxygen emission lines at 495.7 and 500.7  nm . These observed so-called " forbidden lines " occur only in conditions of very low density containing a few atoms per cubic centimeter. In the outer region of the ring, part of

494-538: Is the approximate shape of the ball in several sports, such as in the rugby ball . Several moons of the Solar System approximate prolate spheroids in shape, though they are actually triaxial ellipsoids . Examples are Saturn 's satellites Mimas , Enceladus , and Tethys and Uranus ' satellite Miranda . In contrast to being distorted into oblate spheroids via rapid rotation, celestial objects distort slightly into prolate spheroids via tidal forces when they orbit

532-513: The Equator and 6,356.752 km (3,949.903 mi) at the poles . The word spheroid originally meant "an approximately spherical body", admitting irregularities even beyond the bi- or tri-axial ellipsoidal shape; that is how the term is used in some older papers on geodesy (for example, referring to truncated spherical harmonic expansions of the Earth's gravity geopotential model ). The equation of

570-974: The Maclaurin spheroid and the Jacobi ellipsoid . Spheroid is also a shape of archaeological artifacts. The oblate spheroid is the approximate shape of rotating planets and other celestial bodies , including Earth, Saturn , Jupiter , and the quickly spinning star Altair . Saturn is the most oblate planet in the Solar System , with a flattening of 0.09796. See planetary flattening and equatorial bulge for details. Enlightenment scientist Isaac Newton , working from Jean Richer 's pendulum experiments and Christiaan Huygens 's theories for their interpretation, reasoned that Jupiter and Earth are oblate spheroids owing to their centrifugal force . Earth's diverse cartographic and geodetic systems are based on reference ellipsoids , all of which are oblate. The prolate spheroid

608-400: The actinide and lanthanide elements are shaped like prolate spheroids. In anatomy, near-spheroid organs such as testis may be measured by their long and short axes . Many submarines have a shape which can be described as prolate spheroid. For a spheroid having uniform density, the moment of inertia is that of an ellipsoid with an additional axis of symmetry. Given a description of

646-418: The asteroid 7359 Messier were named in his honour. Prolate spheroid A spheroid , also known as an ellipsoid of revolution or rotational ellipsoid , is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters . A spheroid has circular symmetry . If the ellipse is rotated about its major axis ,

684-472: The figure of the Earth (and of all planets ) is not quite a sphere, but instead is slightly flattened in the direction of its axis of rotation. For that reason, in cartography and geodesy the Earth is often approximated by an oblate spheroid, known as the reference ellipsoid , instead of a sphere. The current World Geodetic System model uses a spheroid whose radius is 6,378.137 km (3,963.191 mi) at

722-399: The ellipse. The volume inside a spheroid (of any kind) is If A = 2 a is the equatorial diameter, and C = 2 c is the polar diameter, the volume is Let a spheroid be parameterized as where β is the reduced latitude or parametric latitude , λ is the longitude , and − ⁠ π / 2 ⁠ < β < + ⁠ π / 2 ⁠ and −π < λ < +π . Then,

760-610: The employ of Joseph Nicolas Delisle , the astronomer of the French Navy , who instructed him to keep careful records of his observations. Messier's first documented observation was that of the Mercury transit of 6 May 1753, followed by his observations journals at Cluny Hotel and at the French Navy observatories. In 1764, Messier was made a fellow of the Royal Society ; in 1769, he

798-458: The end of his life, Messier self-published a booklet connecting the great comet of 1769 to the birth of Napoleon , who was in power at the time of publishing. According to Maik Meyer : As hard as it may seem to accept, the memoir is an ingratiation to Napoleon in order to receive attention and monetary support. It is full of servility and opportunism. Messier did not even refrain from utilizing astrology to reach his goal. Messier comes quickly to

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836-570: The equatorial length: The first eccentricity (usually simply eccentricity, as above) is often used instead of flattening. It is defined by: The relations between eccentricity and flattening are: All modern geodetic ellipsoids are defined by the semi-major axis plus either the semi-minor axis (giving the aspect ratio), the flattening, or the first eccentricity. While these definitions are mathematically interchangeable, real-world calculations must lose some precision. To avoid confusion, an ellipsoidal definition considers its own values to be exact in

874-588: The faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes, and said he could no longer find the central star. In 1864, English amateur astronomer William Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities. The nebula

912-411: The final version was published. These seven objects, M 104 through M 110 , are accepted by astronomers as "official" Messier objects. The objects' Messier designations, from M 1 to M 110 , are still used by professional and amateur astronomers today and their relative brightness makes them popular objects in the amateur astronomical community. The lunar crater Messier and

950-522: The form it gives. The most common shapes for the density distribution of protons and neutrons in an atomic nucleus are spherical , prolate, and oblate spheroidal, where the polar axis is assumed to be the spin axis (or direction of the spin angular momentum vector). Deformed nuclear shapes occur as a result of the competition between electromagnetic repulsion between protons, surface tension and quantum shell effects . Spheroids are common in 3D cell cultures . Rotating equilibrium spheroids include

988-448: The knots' tips that face the central star; however, most of these knots are neutral and appear only in extinction lines. Their existence shows they are probably only located closer to the ionization front than those found in the Lupus planetary IC 4406 . Some of the knots do exhibit well-developed tails which are often detectable in optical thickness from the visual spectrum. The central star

1026-548: The point on the first page of the memoir, by stating that the beginning of the epoch of Napoleon the Great ... coincides with the discovery of one of the greatest comets ever observed. Messier is buried in Père Lachaise Cemetery in the 20th arrondissement of Paris. Messier's occupation as a comet hunter led him to continually come across fixed diffuse objects in the night sky which could be mistaken for comets. He compiled

1064-537: The reddish hue is caused by hydrogen emission at 656.3 nm, forming part of the Balmer series of lines. Forbidden lines of ionized nitrogen or N II contribute to the reddishness at 654.8 and 658.3 nm. M57 is of the class of such starburst nebulae known as bipolar , whose thick equatorial rings visibly extend the structure through its main axis of symmetry. It appears to be a prolate spheroid with strong concentrations of material along its equator . From Earth,

1102-456: The result is a prolate spheroid , elongated like a rugby ball . The American football is similar but has a pointier end than a spheroid could. If the ellipse is rotated about its minor axis , the result is an oblate spheroid , flattened like a lentil or a plain M&;M . If the generating ellipse is a circle, the result is a sphere . Due to the combined effects of gravity and rotation ,

1140-486: The smaller oblate distortion from the synchronous rotation to cause the body to become triaxial. The term is also used to describe the shape of some nebulae such as the Crab Nebula . Fresnel zones , used to analyze wave propagation and interference in space, are a series of concentric prolate spheroids with principal axes aligned along the direct line-of-sight between a transmitter and a receiver. The atomic nuclei of

1178-399: The spheroid's Gaussian curvature is and its mean curvature is Both of these curvatures are always positive, so that every point on a spheroid is elliptic. The aspect ratio of an oblate spheroid/ellipse, c  : a , is the ratio of the polar to equatorial lengths, while the flattening (also called oblateness ) f , is the ratio of the equatorial-polar length difference to

Ring Nebula - Misplaced Pages Continue

1216-429: The symmetrical axis is viewed at about 30°. Overall, the observed nebulosity has been currently estimated to be expanding for approximately 1,610 ± 240 years. Structural studies find this planetary nebula exhibits knots characterized by well-developed symmetry. However, these are only silhouettes visible against the background emission of the nebula's equatorial ring. M57 may include internal N II emission lines located at

1254-456: Was a French astronomer . He published an astronomical catalogue consisting of 110  nebulae and star clusters , which came to be known as the Messier objects , referred to with the letter M and their number between 1 and 110. Messier's purpose for the catalogue was to help astronomical observers distinguish between permanent and transient visually diffuse objects in the sky . Messier

1292-562: Was born in Badonviller in the Lorraine region of France , in 1730, the tenth of twelve children of Françoise B. Grandblaise and Nicolas Messier, a Court usher . Six of his brothers and sisters died while young, and his father died in 1741. Charles' interest in astronomy was stimulated by the appearance of the great six-tailed comet in 1744 and by an annular solar eclipse visible from his hometown on 25 July 1748. In 1751, Messier entered

1330-515: Was discovered by Hungarian astronomer Jenő Gothard on September 1, 1886, from images taken at his observatory in Herény, near Szombathely . Within the last two thousand years, the central star of the Ring Nebula has left the asymptotic giant branch after exhausting its supply of hydrogen fuel. Thus it no longer produces its energy through nuclear fusion and, in evolutionary terms, it is now becoming

1368-546: Was elected a foreign member of the Royal Swedish Academy of Sciences ; and on 30 June 1770, he was elected to the French Academy of Sciences . He was given the nickname "Ferret of Comets" by King Louis XV . Messier discovered 13 comets: He also co-discovered Comet C/1801 N1 ( Comet Pons-Messier-Méchain-Bouvard ), a discovery shared with several other observers including Pons , Méchain, and Bouvard. Near

1406-576: Was first photographed by the Hungarian astronomer Eugene von Gothard in 1886. M57 is found south of the bright star Vega , which forms the northwestern vertex of the Summer Triangle asterism. The nebula lies about 40% of the distance from Beta (β) to Gamma (γ) Lyrae, making it an easy target for amateur astronomers to find. The nebula disk has an angular size of 1.5 × 1 arcminutes , making it too small to be resolved with 10×50 binoculars . It

1444-714: Was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being discovered by Messier himself. By 1780 the catalog had increased to 80 objects. The final version of the catalogue was published in 1781, in the 1784 issue of Connaissance des Temps . The final list of Messier objects had grown to 103. On several occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven objects that were observed either by Messier or by Méchain, shortly after

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