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Orcus-Vanth
Orcus (minor-planet designation 90482 Orcus, provisional designation ) is a trans-Neptunian dwarf planet with a large moon, Vanth. It has a diameter of . The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004. Orcus is a plutino, a trans-Neptunian object that is locked in a 2:3 resonance with the ice giant Neptune, making two revolutions around the Sun to every three of Neptune's. This is much like Pluto, except that the phase of Orcus's orbit is opposite to Pluto's: Orcus is at aphelion (most recently in 2019) around when Pluto is at perihelion (most recently in 1989) and vice versa. Orcus is the largest known plutino after Pluto i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vanth (moon)
Vanth, full designation , is the single known natural satellite of the plutino and likely dwarf planet 90482 Orcus. With a diameter of about 440 km, it is half the size of Orcus and probably the third-largest known moon of a known trans-Neptunian object, after Pluto I Charon and Eris I Dysnomia, though it is possible that the poorly resolved Varda I Ilmarë or Haumea I Hiiaka might be comparable in size. Vanth was discovered by Michael Brown and T.-A. Suer using discovery images taken by the Hubble Space Telescope on 13 November 2005. The discovery was announced in an IAU Circular notice published on 22 February 2007. Using observations with the Hubble Space Telescope from 13 November 2005, Michael Brown and T. A. Suer detected a natural satellite. The discovery of a satellite of Orcus was reported in an IAU Circular notice published on 22 February 2007. The satellite was given the designation S/2005 (90482) 1 before later being named ''Vanth''. It orbits Orcus in a near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwarf Planet
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to planetary geologists is that they may be geologically active bodies, an expectation that was borne out in 2015 by the ''Dawn'' mission to and the '' New Horizons'' mission to Pluto. Astronomers are in general agreement that at least the nine largest candidates are dwarf planets: Pluto, , , , , , , , and . Of these and the tenth-largest candidate , all but Sedna have either been visited by spacecraft (Pluto and Ceres) or have at least one known moon (Pluto, Eris, Haumea, Makemake, Gonggong, Quaoar, Orcus, and Salacia), which allows their masses and thus an estimate of their densities to be determined. Mass and density in turn can be fit into geophysical models in an attempt to determine the nature of these worlds. Some astronomers include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orcus Symbol (bold)
Orcus ( la, Orcus) was a god of the underworld, punisher of broken oaths in Etruscan and Roman mythology. As with Hades, the name of the god was also used for the underworld itself. In the later tradition, he was conflated with Dis Pater. A temple to Orcus may once have existed on the Palatine Hill in Rome. It is likely that he was transliterated from the Greek daemon Horkos, the personification of oaths and a son of Eris. Origins The origins of Orcus may have lain in Etruscan religion. The so-called “ Tomb of Orcus”, an Etruscan site at Tarquinia, is a misnomer, resulting from its first discoverers mistaking a hairy, bearded giant for Orcus; it actually depicts a Cyclops. The Romans sometimes conflated Orcus with other gods such as Pluto, Hades, and Dis Pater, all gods of the underworld. The name “Orcus” seems to have been given to the malicious and punishing side of the ruler of the underworld, as the god who tormented evildoers in their afterlife. Like the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. Surface albedo is defined as the ratio of Radiosity (radiometry), radiosity ''J''e to the irradiance ''E''e (flux per unit area) received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of the world, the lives and activities of List of Greek mythological figures, deities, Greek hero cult, heroes, and List of Greek mythological creatures, mythological creatures, and the origins and significance of the ancient Greeks' own cult (religious practice), cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of myth-making itself. The Greek myths were initially propagated in an oral tradition, oral-poetic tradition most likely by Minoan civilization, Minoan and Mycenaean Greece, Mycenaean singers starting in the 18th century BC; eventually the myths of the heroes of the Trojan War and its after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etruscan Mythology
Etruscan religion comprises a set of stories, beliefs, and religious practices of the Etruscan civilization, heavily influenced by the mythology of ancient Greece, and sharing similarities with concurrent Roman mythology and religion. As the Etruscan civilization was gradually assimilated into the Roman Republic from the 4th century BC, the Etruscan religion and mythology were partially incorporated into ancient Roman culture, following the Roman tendency to absorb some of the local gods and customs of conquered lands. The first attestations of an Etruscan religion can be traced back to the Villanovan culture. History Greek influence Greek traders brought their religion and hero figures with them to the coastal areas of the central Mediterranean. Odysseus, Menelaus and Diomedes from the Homeric tradition were recast in tales of the distant past that had them roaming the lands West of Greece. In Greek tradition, Heracles wandered these western areas, doing away with monsters ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roman Mythology
Roman mythology is the body of myths of ancient Rome as represented in the literature and visual arts of the Romans. One of a wide variety of genres of Roman folklore, ''Roman mythology'' may also refer to the modern study of these representations, and to the subject matter as represented in the literature and art of other cultures in any period. Roman mythology draws from the mythology of the Italic peoples and ultimately from Proto-Indo-European mythology. Roman mythology also draws directly on Greek mythology, potentially as early as Rome's protohistory, but primarily during the Hellenistic period of Greek influence and through the Roman conquest of Greece, via the artistic imitation of Greek literary models by Roman authors. The Romans identified their own gods with those of the ancient Greeks—who were closely historically related in some cases, such as Zeus and Jupiter—and reinterpreted myths about Greek deities under the names of their Roman counterparts. Greek and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charon (moon)
Charon ( or ), known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto. It has a mean radius of . Charon is the sixth-largest known trans-Neptunian object after Pluto, Eris, Haumea, Makemake and Gonggong. It was discovered in 1978 at the United States Naval Observatory in Washington, D.C., using photographic plates taken at the United States Naval Observatory Flagstaff Station (NOFS). With half the diameter and one eighth the mass of Pluto, Charon is a very large moon in comparison to its parent body. Its gravitational influence is such that the barycenter of the Plutonian system lies outside Pluto, and the two bodies are tidally locked to each other. The reddish-brown cap of the north pole of Charon is composed of tholins, organic macromolecules that may be essential ingredients of life. These tholins were produced from methane, nitrogen and related gases which may have been released by cryovolcanic eruptions on the moon, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perihelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elliptic orbit. The name for each apsis is created from the prefixes ''ap-'', ''apo-'' (), or ''peri-'' (), each referring to the farthest and closest point to the primary body the affixing necessary suffix that describes the primary body in the orbit. In this case, the suffix for Earth is ''-gee'', so the apsides' names are ''apogee'' and ''perigee''. For the Sun, its suffix is ''-helion'', so the names are ''aphelion'' and ''perihelion''. According to Newton's laws of motion, all periodic orbits are ellipses. The barycenter of the two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass, the smaller mass is negligible (e.g., f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aphelion
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elliptic orbit. The name for each apsis is created from the prefixes ''ap-'', ''apo-'' (), or ''peri-'' (), each referring to the farthest and closest point to the primary body the affixing necessary suffix that describes the primary body in the orbit. In this case, the suffix for Earth is ''-gee'', so the apsides' names are ''apogee'' and ''perigee''. For the Sun, its suffix is ''-helion'', so the names are ''aphelion'' and ''perihelion''. According to Newton's laws of motion, all periodic orbits are ellipses. The barycenter of the two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass, the smaller mass is negligible (e.g., f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (waves)
In physics and mathematics, the phase of a periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is denoted \phi(t) and expressed in such a scale that it varies by one full turn as the variable t goes through each period (and F(t) goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or 2\pi as the variable t completes a full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t then can be expressed as \phi(t), the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing the phase; so that \phi(t) is also a periodic function, with the same period as F, that repeatedly scans the same range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is slightly less massive than Eris (dwarf planet), Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Compared to Moon, Earth's moon, Pluto has only one sixth its mass and one third its volume. Pluto has a moderately orbital eccentricity, eccentric and inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its average distance (). Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stable orbital resonance prevents them from colliding. Pluto has moons of Pluto, five known moons: Charon (moon), Charon, the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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