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Maxwell Gap and Ringlet
The Maxwell Gap lies within the outer part of the C Ring. It also contains a dense non-circular ringlet, the Maxwell Ringlet. In many respects this ringlet is similar to the ε ring of Uranus. There are wave-like structures in the middle of both rings. While the wave in the ε ring is thought to ... | Rings of Saturn | Wikipedia | 374 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Until 1980, the structure of the rings of Saturn was explained as being caused exclusively by the action of gravitational forces. Then images from the Voyager spacecraft showed radial features in the B Ring, known as spokes, which could not be explained in this manner, as their persistence and rotation around the rings... | Rings of Saturn | Wikipedia | 446 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The Cassini Division is a region in width between Saturn's A Ring and B Ring. It was discovered in 1675 by Giovanni Cassini at the Paris Observatory using a refracting telescope that had a 2.5-inch objective lens with a 20-foot-long focal length and a 90x magnification. From Earth it appears as a thin black gap in the... | Rings of Saturn | Wikipedia | 471 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Similarly to the B Ring, the A Ring's outer edge is maintained by orbital resonances, albeit in this case a more complicated set. It is primarily acted on by the 7:6 resonance with Janus and Epimetheus, with other contributions from the 5:3 resonance with Mimas and various resonances with Prometheus and Pandora. Other ... | Rings of Saturn | Wikipedia | 411 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The Keeler Gap is a 42-km (26 mile) wide gap in the A ring, approximately 250 km (150 miles) from the ring's outer edge. The small moon Daphnis, discovered 1 May 2005, orbits within it, keeping it clear. The moon's passage induces waves in the edges of the gap (this is also influenced by its slight orbital eccentricity... | Rings of Saturn | Wikipedia | 427 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Like the Cassini Division, the Roche Division is not empty but contains a sheet of material. The character of this material is similar to the tenuous and dusty D, E, and G Rings. Two locations in the Roche Division have a higher concentration of dust than the rest of the region. These were discovered by the Cassini pro... | Rings of Saturn | Wikipedia | 438 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
As of 2023, the clumpy structure of the ring "is thought to be caused by the presence of thousands of small parent bodies (1.0 to 0.1 km in size) that collide and produce dense strands of micrometer- to centimeter-sized particles that re-accrete over a few months onto the parent bodies in a steady-state regime."
Outer... | Rings of Saturn | Wikipedia | 484 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Methone Ring Arc
A faint ring arc, first detected in September 2006, covering a longitudinal extent of about 10 degrees is associated with the moon Methone. The material in the arc is believed to represent dust ejected from Methone by micrometeoroid impacts. The confinement of the dust within the arc is attributable t... | Rings of Saturn | Wikipedia | 294 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Although not confirmed until 1980, the existence of the E ring was a subject of debate among astronomers at least as far back as 1908. In a narrative timeline of Saturn observations, Arthur Francis O'Donel Alexander attributes the first observation of what would come to be called the E Ring to Georges Fournier, who on ... | Rings of Saturn | Wikipedia | 267 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Unlike the A, B, and C rings, the E Ring's small optical depth and large vertical extent mean it is best viewed edge-on, which is only possible once every 14–15 years, so perhaps for this reason, it was not until the 1960's that the E Ring was again the subject of observations. Although some sources credit Walter Feibe... | Rings of Saturn | Wikipedia | 438 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Particles of the E Ring tend to accumulate on moons that orbit within it. The equator of the leading hemisphere of Tethys is tinted slightly blue due to infalling material. The trojan moons Telesto, Calypso, Helene and Polydeuces are particularly affected as their orbits move up and down the ring plane. This results in... | Rings of Saturn | Wikipedia | 478 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The existence of the ring was proposed in the 1970s by Steven Soter. The discovery was made by Anne J. Verbiscer and Michael F. Skrutskie (of the University of Virginia) and Douglas P. Hamilton (of the University of Maryland, College Park). The three had studied together at Cornell University as graduate students.
Rin... | Rings of Saturn | Wikipedia | 268 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Saturn's second largest moon Rhea has been hypothesized to have a tenuous ring system of its own consisting of three narrow bands embedded in a disk of solid particles. These putative rings have not been imaged, but their existence has been inferred from Cassini observations in November 2005 of a depletion of energetic... | Rings of Saturn | Wikipedia | 253 | 977592 | https://en.wikipedia.org/wiki/Rings%20of%20Saturn | Physical sciences | Solar System | Astronomy |
A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a sharp snapping sound.
When used in materials... | Brittleness | Wikipedia | 424 | 978913 | https://en.wikipedia.org/wiki/Brittleness | Physical sciences | Solid mechanics | Physics |
When a material has reached the limit of its strength, it usually has the option of either deformation or fracture. A naturally malleable metal can be made stronger by impeding the mechanisms of plastic deformation (reducing grain size, precipitation hardening, work hardening, etc.), but if this is taken to an extreme,... | Brittleness | Wikipedia | 501 | 978913 | https://en.wikipedia.org/wiki/Brittleness | Physical sciences | Solid mechanics | Physics |
The rings of Jupiter are a system of faint planetary rings. The Jovian rings were the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. The main ring was discovered in 1979 by the Voyager 1 space probe and the system was more thoroughly investigated in the 1990s by the Galileo or... | Rings of Jupiter | Wikipedia | 416 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Discovery and structure
Jupiter's ring system was the third to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed on 4 March 1979 by the Voyager 1 space probe. It is composed of four main components: a thick inner torus of particles known as the "halo ring"; a relatively bright, ... | Rings of Jupiter | Wikipedia | 404 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
In back-scattered light the situation is different. The outer boundary of the main ring, located at , or slightly beyond the orbit of Adrastea, is very steep. The orbit of the moon is marked by a gap in the ring so there is a thin ringlet just outside its orbit. There is another ringlet just inside Adrastean orbit foll... | Rings of Jupiter | Wikipedia | 464 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
In February–March 2007 New Horizons spacecraft conducted a deep search for new small moons inside the main ring. While no satellites larger than 0.5 km were found, the cameras of the spacecraft detected seven small clumps of ring particles. They orbit just inside the orbit of Adrastea inside a dense ringlet. The conclu... | Rings of Jupiter | Wikipedia | 501 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The power law mentioned above allows estimation of the optical depth of the main ring: for the large bodies and for the dust. This optical depth means that the total cross section of all particles inside the ring is about 5000 km². The particles in the main ring are expected to have aspherical shapes. The total mass... | Rings of Jupiter | Wikipedia | 489 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Vertical corrugations
Images from the Galileo and New Horizons space probes show the presence of two sets of spiraling vertical corrugations in the main ring. These waves became more tightly wound over time at the rate expected for differential nodal regression in Jupiter's gravity field. Extrapolating backwards, the m... | Rings of Jupiter | Wikipedia | 373 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The halo ring appears brightest in forward-scattered light, in which it was extensively imaged by Galileo. While its surface brightness is much less than that of the main ring, its vertically (perpendicular to the ring plane) integrated photon flux is comparable due to its much larger thickness. Despite a claimed verti... | Rings of Jupiter | Wikipedia | 489 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The Amalthea gossamer ring is a very faint structure with a rectangular cross section, stretching from the orbit of Amalthea at (2.54 RJ) to about (). Its inner boundary is not clearly defined because of the presence of the much brighter main ring and halo. The thickness of the ring is approximately 2300 km near the ... | Rings of Jupiter | Wikipedia | 428 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Thebe gossamer ring
The Thebe gossamer ring is the faintest Jovian ring. It appears as a very faint structure with a rectangular cross section, stretching from the Thebean orbit at () to about (;). Its inner boundary is not clearly defined because of the presence of the much brighter main ring and halo. The thickness... | Rings of Jupiter | Wikipedia | 360 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Origin of the gossamer rings
The dust in the gossamer rings originates in essentially the same way as that in the main ring and halo. Its sources are the inner Jovian moons Amalthea and Thebe respectively. High velocity impacts by projectiles coming from outside the Jovian system eject dust particles from their surface... | Rings of Jupiter | Wikipedia | 446 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
In September 2006, as NASA's New Horizons mission to Pluto approached Jupiter for a gravity assist, it photographed what appeared to be a faint, previously unknown planetary ring or ring arc, parallel with and slightly inside the orbit of the irregular satellite Himalia. The amount of material in the part of the ring o... | Rings of Jupiter | Wikipedia | 355 | 979227 | https://en.wikipedia.org/wiki/Rings%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The rings of Uranus consists of 13 planetary rings. They are intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Jessica Mink. William Herschel had al... | Rings of Uranus | Wikipedia | 443 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The mechanism that confines the narrow rings is not well understood. Initially it was assumed that every narrow ring had a pair of nearby shepherd moons corralling it into shape. In 1986 Voyager 2 discovered only one such shepherd pair (Cordelia and Ophelia) around the brightest ring (ε), though the faint ν would later... | Rings of Uranus | Wikipedia | 264 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The definitive discovery of the Uranian rings was made by astronomers James L. Elliot, Edward W. Dunham, and Jessica Mink on March 10, 1977, using the Kuiper Airborne Observatory, and was serendipitous. They planned to use the occultation of the star SAO 158687 by Uranus to study the planet's atmosphere. When their obs... | Rings of Uranus | Wikipedia | 380 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
As currently understood, the ring system of Uranus comprises thirteen distinct rings. In order of increasing distance from the planet they are: 1986U2R/ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν, μ rings. They can be divided into three groups: nine narrow main rings (6, 5, 4, α, β, η, γ, δ, ε), two dusty rings (1986U2R/ζ, λ) a... | Rings of Uranus | Wikipedia | 473 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
As a whole, the ring system of Uranus is unlike either the faint dusty rings of Jupiter or the broad and complex rings of Saturn, some of which are composed of very bright material—water ice. There are similarities with some parts of the latter ring system; the Saturnian F ring and the Uranian ε ring are both narrow, r... | Rings of Uranus | Wikipedia | 462 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The geometric thickness of the ε ring is not precisely known, although the ring is certainly very thin—by some estimates as thin as 150 m. Despite such infinitesimal thickness, it consists of several layers of particles. The ε ring is a rather crowded place with a filling factor near the apoapsis estimated by different... | Rings of Uranus | Wikipedia | 369 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The δ ring is circular and slightly inclined. It shows significant unexplained azimuthal variations in normal optical depth and width. One possible explanation is that the ring has an azimuthal wave-like structure, excited by a small moonlet just inside it. The sharp outer edge of the δ ring is in 23:22 resonance with ... | Rings of Uranus | Wikipedia | 445 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
η (eta) ring
The η ring has zero orbital eccentricity and inclination. Like the δ ring, it consists of two components: a narrow optically dense component and a broad outward shoulder with low optical depth. The width of the narrow component is 1.9–2.7 km and the equivalent depth is about 0.42 km, which corresponds to t... | Rings of Uranus | Wikipedia | 322 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
α (alpha) and β (beta) rings
After the ε ring, the α and β rings are the brightest of Uranus' rings. Like the ε ring, they exhibit regular variations in brightness and width. They are brightest and widest 30° from the apoapsis and dimmest and narrowest 30° from the periapsis. The α and β rings have sizable orbital ecce... | Rings of Uranus | Wikipedia | 452 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The λ ring was one of two rings discovered by Voyager 2 in 1986. It is a narrow, faint ring located just inside the ε ring, between it and the shepherd moon Cordelia. This moon clears a dark lane just inside the λ ring. When viewed in back-scattered light, the λ ring is extremely narrow—about 1–2 km—and has the equival... | Rings of Uranus | Wikipedia | 370 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
In 1986 Voyager 2 detected a broad and faint sheet of material inward of ring 6. This ring was given the temporary designation 1986U2R. It had a normal optical depth of 10−3 or less and was extremely faint. It was thought to be visible only in a single Voyager 2 image, until reanalysis of Voyager data in 2022 revealed ... | Rings of Uranus | Wikipedia | 361 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
Other dust bands
In addition to the 1986U2R/ζ and λ rings, there are other extremely faint dust bands in the Uranian ring system. They are invisible during occultations because they have negligible optical depth, though they are bright in forward-scattered light. Voyager 2'''s images of forward-scattered light revealed... | Rings of Uranus | Wikipedia | 393 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The peak brightness of the μ (mu) ring lies almost exactly on the orbit of the small Uranian moon Mab, which is probably the source of the ring’s particles. The ν (nu) ring is positioned between Portia and Rosalind and does not contain any moons inside it. A reanalysis of the Voyager 2 images of forward-scattered light... | Rings of Uranus | Wikipedia | 512 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
Since the rings of Uranus appear to be young, they must be continuously renewed by the collisional fragmentation of larger bodies. The estimates show that the lifetime against collisional disruption of a moon with the size like that of Puck is a few billion years. The lifetime of a smaller satellite is much shorter. Th... | Rings of Uranus | Wikipedia | 502 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
List of properties
This table summarizes the properties of the planetary ring system of Uranus. | Rings of Uranus | Wikipedia | 19 | 979232 | https://en.wikipedia.org/wiki/Rings%20of%20Uranus | Physical sciences | Solar System | Astronomy |
The rings of Neptune consist primarily of five principal rings. They were first discovered (as "arcs") by simultaneous observations of a stellar occultation on 22 July 1984 by André Brahic's and William B. Hubbard's teams at La Silla Observatory (ESO) and at Cerro Tololo Interamerican Observatory in Chile. They were ev... | Rings of Neptune | Wikipedia | 363 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
The first mention of rings around Neptune dates back to 1846 when William Lassell, the discoverer of Neptune's largest moon, Triton, thought he had seen a ring around the planet. However, his claim was never confirmed and it is likely that it was an observational artifact. The first reliable detection of a ring was mad... | Rings of Neptune | Wikipedia | 412 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
Since Voyager 2s fly-by, the brightest rings (Adams and Le Verrier) have been imaged with the Hubble Space Telescope and Earth-based telescopes, owing to advances in resolution and light-gathering power. They are visible, slightly above background noise levels, at methane-absorbed wavelengths in which the glare from Ne... | Rings of Neptune | Wikipedia | 397 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
The Neptunian rings contain a large quantity of micrometer-sized dust: the dust fraction by cross-section area is between 20% and 70%. In this respect they are similar to the rings of Jupiter, in which the dust fraction is 50%–100%, and are very different from the rings of Saturn and Uranus, which contain little dust (... | Rings of Neptune | Wikipedia | 416 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
Le Verrier ring
The next ring is named the Le Verrier ring after Urbain Le Verrier, who predicted Neptune's position in 1846. With an orbital radius of about 53,200 km, it is narrow, with a width of about 113 km. Its normal optical depth is 0.0062 ± 0.0015, which corresponds to an equivalent depth of 0.7 ± 0.2 km. The... | Rings of Neptune | Wikipedia | 333 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
The outer Adams ring, with an orbital radius of about 63,930 km, is the best studied of Neptune's rings. It is named after John Couch Adams, who predicted the position of Neptune independently of Le Verrier. This ring is narrow, slightly eccentric and inclined, with total width of about 35 km (15–50 km), and its normal... | Rings of Neptune | Wikipedia | 504 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
The highest resolution Voyager 2 images revealed a pronounced clumpiness in the arcs, with a typical separation between visible clumps of 0.1° to 0.2°, which corresponds to 100–200 km along the ring. Because the clumps were not resolved, they may or may not include larger bodies, but are certainly associated with conce... | Rings of Neptune | Wikipedia | 437 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
A later model suggested that confinement resulted from a co-rotational eccentricity resonance (CER). The model takes into account the finite mass of the Adams ring, which is necessary to move the resonance closer to the ring. A byproduct of this hypothesis is a mass estimate for the Adams ring—about 0.002 of the mass o... | Rings of Neptune | Wikipedia | 330 | 979237 | https://en.wikipedia.org/wiki/Rings%20of%20Neptune | Physical sciences | Solar System | Astronomy |
In astrodynamics, orbital station-keeping is keeping a spacecraft at a fixed distance from another spacecraft or celestial body. It requires a series of orbital maneuvers made with thruster burns to keep the active craft in the same orbit as its target. For many low Earth orbit satellites, the effects of non-Keplerian ... | Orbital station-keeping | Wikipedia | 496 | 979306 | https://en.wikipedia.org/wiki/Orbital%20station-keeping | Physical sciences | Orbital mechanics | Astronomy |
For spacecraft in a very low orbit, the atmospheric drag is sufficiently strong to cause a re-entry before the intended end of mission if orbit raising maneuvers are not executed from time to time.
An example of this is the International Space Station (ISS), which has an operational altitude above Earth's surface of b... | Orbital station-keeping | Wikipedia | 452 | 979306 | https://en.wikipedia.org/wiki/Orbital%20station-keeping | Physical sciences | Orbital mechanics | Astronomy |
For geostationary spacecraft, thruster burns orthogonal to the orbital plane must be executed to compensate for the effect of the lunar/solar gravitation that perturbs the orbit pole with typically 0.85 degrees per year. The delta-v needed to compensate for this perturbation keeping the inclination to the equatorial pl... | Orbital station-keeping | Wikipedia | 456 | 979306 | https://en.wikipedia.org/wiki/Orbital%20station-keeping | Physical sciences | Orbital mechanics | Astronomy |
One important Lagrange point is Earth-Sun , and three heliophysics missions have been orbiting L1 since approximately 2000. Station-keeping propellant use can be quite low, facilitating missions that can potentially last decades should other spacecraft systems remain operational. The three spacecraft—Advanced Composi... | Orbital station-keeping | Wikipedia | 306 | 979306 | https://en.wikipedia.org/wiki/Orbital%20station-keeping | Physical sciences | Orbital mechanics | Astronomy |
The Sculptor Galaxy (also known as the Silver Coin Galaxy, Silver Dollar Galaxy, NGC 253, or Caldwell 65) is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.
Observation
Observational... | Sculptor Galaxy | Wikipedia | 463 | 979452 | https://en.wikipedia.org/wiki/Sculptor%20Galaxy | Physical sciences | Notable galaxies | Astronomy |
The Sculptor Galaxy is located at the center of the Sculptor Group, one of the nearest groups of galaxies to the Milky Way. The Sculptor Galaxy (the brightest galaxy in the group and one of the intrinsically brightest galaxies in the vicinity of ours, only surpassed by the Andromeda Galaxy and the Sombrero Galaxy) and ... | Sculptor Galaxy | Wikipedia | 485 | 979452 | https://en.wikipedia.org/wiki/Sculptor%20Galaxy | Physical sciences | Notable galaxies | Astronomy |
NGC 253 is close enough that classical novae can also be detected. The first confirmed nova in this galaxy was discovered by BlackGEM at magnitude 19.6 on 12 July 2024, and designated AT 2024pid.
Central black hole
Research suggests the presence of a supermassive black hole in the center of this galaxy with a mass es... | Sculptor Galaxy | Wikipedia | 292 | 979452 | https://en.wikipedia.org/wiki/Sculptor%20Galaxy | Physical sciences | Notable galaxies | Astronomy |
The Bosphorus Bridge (), known officially as the 15 July Martyrs Bridge () and colloquially as the First Bridge (), is the oldest and southernmost of the three suspension bridges spanning the Bosphorus strait (Turkish: Boğaziçi) in Istanbul, Turkey, thus connecting Europe and Asia (alongside the Fatih Sultan Mehmet Bri... | Bosphorus Bridge | Wikipedia | 421 | 4096049 | https://en.wikipedia.org/wiki/Bosphorus%20Bridge | Technology | Bridges | null |
Precedents and proposals
The idea of a bridge crossing the Bosphorus dates back to antiquity. The Greek writer Herodotus says in his Histories that, on the orders of Emperor Darius the Great of the Achaemenid Empire (522 BC–485 BC), Mandrocles of Samos once engineered a pontoon bridge across the Bosphorus, linking Asia... | Bosphorus Bridge | Wikipedia | 496 | 4096049 | https://en.wikipedia.org/wiki/Bosphorus%20Bridge | Technology | Bridges | null |
The bridge highway is eight lanes wide. Three standard lanes, one emergency lane and one pedestrian lane serve each direction. On weekday mornings, most commuter traffic flows westbound to Europe, so four of the six lanes run westbound and only two eastbound. Conversely, on weekday evenings, four lanes are dedicated to... | Bosphorus Bridge | Wikipedia | 471 | 4096049 | https://en.wikipedia.org/wiki/Bosphorus%20Bridge | Technology | Bridges | null |
In 2017, the toll increased by nearly 50% from 4.75 to 7 TRY. After 21 months, in late 2019, the toll went up another 20% to 10.50 TRY. Tolls need to be increased almost every year to keep up with high producers' price inflation.
Notable events
The bridge was depicted on the reverse of the Turkish 1000 lira banknote... | Bosphorus Bridge | Wikipedia | 391 | 4096049 | https://en.wikipedia.org/wiki/Bosphorus%20Bridge | Technology | Bridges | null |
On 15 July 2016, the bridge was blocked by a rogue faction of the Turkish Armed Forces during a coup attempt. They arrested civilians and police officers. The soldiers involved surrendered to police and to civilians the next day. On 25 July 2016, Binali Yıldırım, Turkey's last prime minister before a presidential syste... | Bosphorus Bridge | Wikipedia | 142 | 4096049 | https://en.wikipedia.org/wiki/Bosphorus%20Bridge | Technology | Bridges | null |
A rocker box (also known as a cradle or a big box) is a gold mining implement for separating alluvial placer gold from sand and gravel which was used in placer mining in the 19th century. It consists of a high-sided box, which is open on one end and on top, and was placed on rockers.
The inside bottom of the box is li... | Rocker box | Wikipedia | 423 | 4101529 | https://en.wikipedia.org/wiki/Rocker%20box | Technology | Metallurgy | null |
Rocker boxes must be manipulated carefully, to prevent losing the gold. Although big, and difficult to move, the rocker can pick up twice the amount of the gravel, and therefore more gold in one day than an ordinary gold mining pan. The rocker, like the pan, is used extensively in small-scale placer work, in sampling,... | Rocker box | Wikipedia | 279 | 4101529 | https://en.wikipedia.org/wiki/Rocker%20box | Technology | Metallurgy | null |
Seine fishing (or seine-haul fishing; ) is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.
Boats deploying sei... | Seine fishing | Wikipedia | 440 | 1513400 | https://en.wikipedia.org/wiki/Seine%20fishing | Technology | Hunting and fishing | null |
A common type of seine is a purse seine, named such because along the bottom are a number of rings. A line (referred to as a purse-line) passes through all the rings, and when pulled, draws the rings close to one another, preventing the fish from "sounding", or swimming down to escape the net. This operation is similar... | Seine fishing | Wikipedia | 490 | 1513400 | https://en.wikipedia.org/wiki/Seine%20fishing | Technology | Hunting and fishing | null |
A minimum of three people are required for power block seining; the skipper, skiff operator, and corkline stacker. In many operations a fourth person stacks the leadline, and often a fifth person stacks the web.
Drum
In certain parts of the western United States as well as Canada, specifically on the coast of British... | Seine fishing | Wikipedia | 444 | 1513400 | https://en.wikipedia.org/wiki/Seine%20fishing | Technology | Hunting and fishing | null |
Danish seining works best on demersal fish which are either scattered on or close to the bottom of the sea, or are aggregated (schooling). They are used when there are flat but rough seabeds which are not trawlable. It is especially useful in northern regions, but not much in tropical to sub-tropical areas.
The net is... | Seine fishing | Wikipedia | 244 | 1513400 | https://en.wikipedia.org/wiki/Seine%20fishing | Technology | Hunting and fishing | null |
Column chromatography in chemistry is a chromatography method used to isolate a single chemical compound from a mixture. Chromatography is able to separate substances based on differential absorption of compounds to the adsorbent; compounds move through the column at different rates, allowing them to be separated into ... | Column chromatography | Wikipedia | 444 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
The individual components are retained by the stationary phase differently and separate from each other while they are running at different speeds through the column with the eluent. At the end of the column they elute one at a time. During the entire chromatography process the eluent is collected in a series of fracti... | Column chromatography | Wikipedia | 372 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
Mobile phase (eluent)
The mobile phase or eluent is a solvent or a mixture of solvents used to move the compounds through the column. It is chosen so that the retention factor value of the compound of interest is roughly around 0.2 - 0.3 in order to minimize the time and the amount of eluent to run the chromatograph... | Column chromatography | Wikipedia | 495 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
A spreadsheet that assists in the successful development of flash columns has been developed. The spreadsheet estimates the retention volume and band volume of analytes, the fraction numbers expected to contain each analyte, and the resolution between adjacent peaks. This information allows users to select optimal para... | Column chromatography | Wikipedia | 412 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
Typically, column chromatography is set up with peristaltic pumps, flowing buffers and the solution sample through the top of the column. The solutions and buffers pass through the column where a fraction collector at the end of the column setup collects the eluted samples. Prior to the fraction collection, the samples... | Column chromatography | Wikipedia | 408 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
A simplified method of calculating chromatogram resolution is to use the plate model. The plate model assumes that the column can be divided into a certain number of sections, or plates and the mass balance can be calculated for each individual plate. This approach approximates a typical chromatogram curve as a Gaussia... | Column chromatography | Wikipedia | 508 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
[CS] = Keq[C].
For industrial scale uses, the total binding molecules on the column resin beads must be factored in because unoccupied sites must be taken into account. The Langmuir isotherm and Freundlich isotherm are useful in describing this equilibrium. The Langmuir isotherm is given by:
[CS] = (KeqStot[C])/(1 + ... | Column chromatography | Wikipedia | 205 | 1514469 | https://en.wikipedia.org/wiki/Column%20chromatography | Physical sciences | Chromatography | Chemistry |
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can be described according to the types of plate margin that meet at them (e.g. fault–... | Triple junction | Wikipedia | 349 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
Interpretation
The properties of triple junctions are most easily understood from the purely kinematic point of view where the plates are rigid and moving over the surface of the Earth. No knowledge of the Earth's interior or the geological details of the crust are then needed. Another useful simplification is that the... | Triple junction | Wikipedia | 457 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
McKenzie and Morgan first analysed the stability of triple junctions using these assumptions with the additional assumption that the Euler poles describing the motions of the plates were such that they approximated to straight line motion on a flat surface. This simplification applies when the Euler poles are distant f... | Triple junction | Wikipedia | 433 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
For a ridge the line constructed must be the perpendicular bisector of the relative motion vector as to remain in the middle of the ridge an observer would have to move at half the relative speeds of the plates either side but could also move in a perpendicular direction along the plate boundary.
For a transform fault... | Triple junction | Wikipedia | 421 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
An RRR junction is always stable using these definitions and therefore very common on Earth, though in a geological sense ridge spreading is usually discontinued in one direction leaving a failed rift zone. There are many examples of these present both now and in the geological past such as the South Atlantic opening w... | Triple junction | Wikipedia | 502 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
The junction of the Red Sea, the Gulf of Aden and the East African Rift centered in the Afar Triangle (the Afar triple junction) is the only R-R-R triple junction above sea level.
The Rodrigues triple junction is a R-R-R triple junction in the southern Indian Ocean, where the African, the Indo-Australian and the Antarc... | Triple junction | Wikipedia | 501 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
The Chile triple junction is where the South American plate, the Nazca plate, and the Antarctic plate meet. | Triple junction | Wikipedia | 23 | 1514751 | https://en.wikipedia.org/wiki/Triple%20junction | Physical sciences | Tectonics | Earth science |
The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation. They were defined by George Gabriel Stokes in 1851, as a mathematically convenient alternative to the more common description of incoherent or partially polarized radiation in terms of its total intensity (I), (... | Stokes parameters | Wikipedia | 451 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
Note that there is an ambiguous sign for the component depending on the physical convention used. In practice, there are two separate conventions used, either defining the Stokes parameters when looking down the beam towards the source (opposite the direction of light propagation) or looking down the beam away from th... | Stokes parameters | Wikipedia | 454 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
The symbols ⟨⋅⟩ represent expectation values. The light can be viewed as a random variable taking values in the space C2 of Jones vectors . Any given measurement yields a specific wave (with a specific phase, polarization ellipse, and magnitude), but it keeps flickering and wobbling between different outcomes. The expe... | Stokes parameters | Wikipedia | 511 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
The Stokes parameters (and thus the polarization of some electromagnetic radiation) can be directly determined from observation. Using a linear polarizer and a quarter-wave plate, the following system of equations relating the Stokes parameters to measured intensity can be obtained:
where is the irradiance of the rad... | Stokes parameters | Wikipedia | 434 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
In the basis of horizontal polarization state and vertical polarization state , the +45° linear polarization state is , the -45° linear polarization state is , the left hand circular polarization state is , and the right hand circular polarization state is . It's easy to see that these states are the eigenvectors of P... | Stokes parameters | Wikipedia | 474 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
The above expression is the theory basis of many polarimeters. For unpolarized light, T=1/2 is a constant. For purely circularly polarized light, T has a sinusoidal dependence on angle θ with a period of 180 degrees, and can reach absolute extinction where T=0. For purely linearly polarized light, T has a sinusoidal de... | Stokes parameters | Wikipedia | 303 | 1515472 | https://en.wikipedia.org/wiki/Stokes%20parameters | Physical sciences | Optics | Physics |
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are operational: the United States's Global Positioning System (GPS), Russia's Glob... | Satellite navigation | Wikipedia | 415 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
is the first generation system and is the combination of existing satellite navigation systems (GPS and GLONASS), with Satellite Based Augmentation Systems (SBAS) or Ground Based Augmentation Systems (GBAS). In the United States, the satellite-based component is the Wide Area Augmentation System (WAAS); in Europe, it i... | Satellite navigation | Wikipedia | 321 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
By their roles in the navigation system, systems can be classified as:
There are four global satellite navigation systems, currently GPS (United States), GLONASS (Russian Federation), Beidou (China) and Galileo (European Union).
Global Satellite-Based Augmentation Systems (SBAS) such as OmniSTAR and StarFire.
Region... | Satellite navigation | Wikipedia | 360 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
The first satellite navigation system was Transit, a system deployed by the US military in the 1960s. Transit's operation was based on the Doppler effect: the satellites travelled on well-known paths and broadcast their signals on a well-known radio frequency. The received frequency will differ slightly from the broad... | Satellite navigation | Wikipedia | 476 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
Each distance measurement, regardless of the system being used, places the receiver on a spherical shell centred on the broadcaster, at the measured distance from the broadcaster. By taking several such measurements and then looking for a point where the shells meet, a fix is generated. However, in the case of fast-mov... | Satellite navigation | Wikipedia | 504 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
The formerly Soviet, and now Russian, Global'naya Navigatsionnaya Sputnikovaya Sistema, (GLObal NAvigation Satellite System or GLONASS), is a space-based satellite navigation system that provides a civilian radionavigation-satellite service and is also used by the Russian Aerospace Defence Forces. GLONASS has full glob... | Satellite navigation | Wikipedia | 390 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
The NavIC (acronym for Navigation with Indian Constellation) is an autonomous regional satellite navigation system developed by the Indian Space Research Organisation (ISRO). The Indian government approved the project in May 2006. It consists of a constellation of 7 navigational satellites. Three of the satellites are ... | Satellite navigation | Wikipedia | 511 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
EGNOS
Comparison of systems
Using multiple GNSS systems for user positioning increases the number of visible satellites, improves precise point positioning (PPP) and shortens the average convergence time.
The signal-in-space ranging error (SISRE) in November 2019 were 1.6 cm for Galileo, 2.3 cm for GPS, 5.2 cm for GL... | Satellite navigation | Wikipedia | 491 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
International regulation
The International Telecommunication Union (ITU) defines a radionavigation-satellite service (RNSS) as "a radiodetermination-satellite service used for the purpose of radionavigation. This service may also include feeder links necessary for its operation".
RNSS is regarded as a safety-of-life s... | Satellite navigation | Wikipedia | 474 | 1515653 | https://en.wikipedia.org/wiki/Satellite%20navigation | Technology | Navigation | null |
Pye-dog, or sometimes pariah dog, is a term used to describe an ownerless, half-wild, free-ranging dog that lives in or close to human settlements throughout Asia. The term is derived from the Sanskrit para, which translates to "outsider".
The United Kennel Club uses the term pariah dog to classify various breeds in a... | Pye-dog | Wikipedia | 82 | 1515866 | https://en.wikipedia.org/wiki/Pye-dog | Biology and health sciences | Dogs | Animals |
Thermodynamics is expressed by a mathematical framework of thermodynamic equations which relate various thermodynamic quantities and physical properties measured in a laboratory or production process. Thermodynamics is based on a fundamental set of postulates, that became the laws of thermodynamics.
Introduction
One ... | Thermodynamic equations | Wikipedia | 456 | 1515898 | https://en.wikipedia.org/wiki/Thermodynamic%20equations | Physical sciences | Thermodynamics | Physics |
A thermodynamic system is in equilibrium when it is no longer changing in time. This may happen in a very short time, or it may happen with glacial slowness. A thermodynamic system may be composed of many subsystems which may or may not be "insulated" from each other with respect to the various extensive quantities. If... | Thermodynamic equations | Wikipedia | 510 | 1515898 | https://en.wikipedia.org/wiki/Thermodynamic%20equations | Physical sciences | Thermodynamics | Physics |
Zeroth law of thermodynamics
If A, B, C are thermodynamic systems such that A is in thermal equilibrium with B and B is in thermal equilibrium with C, then A is in thermal equilibrium with C.
The zeroth law is of importance in thermometry, because it implies the existence of temperature scales. In practice, C is a the... | Thermodynamic equations | Wikipedia | 437 | 1515898 | https://en.wikipedia.org/wiki/Thermodynamic%20equations | Physical sciences | Thermodynamics | Physics |
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