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Pisces (constellation)
Pisces is a constellation of the zodiac. Its vast bulk – and main asterism viewed in most European cultures per Greco-Roman antiquity as a distant pair of fishes connected by one cord each that join at an apex – are in the Northern celestial hemisphere. Its old astronomical symbol is (♓︎). Its name is Latin for "fishes". It is between Aquarius (constellation), Aquarius, of similar size, to the southwest and Aries (constellation), Aries, which is smaller, to the east. The ecliptic and the celestial equator intersect within this constellation and in Virgo (constellation), Virgo. This means the sun subsolar point, passes directly overhead of the equator, on average, at approximately this point in the sky, at the March equinox. Features The March equinox is currently located in Pisces, due south of ω Psc, and, due to precession, slowly drifting due west, just below the western fish towards Aquarius (constellation), Aquarius. Stars * Alrescha ("the cord"), ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fishes
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Most f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celestial Equator
The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. This plane of reference bases the equatorial coordinate system. In other words, the celestial equator is an abstract projection of the terrestrial equator into outer space. Due to Earth's axial tilt, the celestial equator is currently inclined by about 23.44° with respect to the ecliptic (the plane of Earth's orbit), but has varied from about 22.0° to 24.5° over the past 5 million years due to perturbation from other planets. An observer standing on Earth's equator visualizes the celestial equator as a semicircle passing through the zenith, the point directly overhead. As the observer moves north (or south), the celestial equator tilts towards the opposite horizon. The celestial equator is defined to be infinitely distant (since it is on the celestial sphere); thus, the ends of the semicircle always intersect the horizon due east and due west, re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omicron Piscium
Omicron Piscium (ο Piscium, abbreviated Omi Psc, ο Psc) is a binary star in the constellation of Pisces. It is visible to the naked eye, having an apparent visual magnitude of 4.27. Based upon an annual parallax shift of 11.67 mas as seen from the Earth, the system is located roughly 280 light-years from the Sun. It is positioned near the ecliptic, so is subject to occultation by the Moon. It is a member of the thin disk population of the Milky Way. The two components are designated Omicron Piscium A (formally named Torcular ) and B. Nomenclature ''ο Piscium'' ( Latinised to ''Omicron Piscium'') is the system's Bayer designation. The designations of the two components as ''Omicron Piscium A'' and ''B'' derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). The system bore the traditional name ''Torcularis septentrionalis'', taken from the 1515 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Cassiopeiae Variable
A Gamma Cassiopeiae variable (γ Cassiopeiae variable) is a type of variable star, named for its prototype γ Cassiopeiae. Variability γ Cassiopeiae variables show irregular changes in brightness on a timescale of decades. These typically have amplitudes of the order of a magnitude. For example, γ Cassiopeiae is usually about magnitude 2.5 and has varied between magnitudes 1.6 and 3.0. The variations are associated with changes in the spectrum between normal absorption spectra and Be star spectra, often also including shell star characteristics. Pleione and γ Cassiopeiae itself are both variable stars that have intermittent shell episodes where strong shell features appear in the spectrum and the brightness increases or decreases significantly. At other times the shell is not detectable in the spectrum, and even the emission lines may disappear. The General Catalogue of Variable Stars (GCVS) categorises γ Cassiopeiae stars as eruptive variables and describes them as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monthly Notices Of The Royal Astronomical Society
''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes letters and papers reporting original research in relevant fields. Despite the name, the journal is no longer monthly, nor does it carry the notices of the Royal Astronomical Society. History The first issue of MNRAS was published on 9 February 1827 as ''Monthly Notices of the Astronomical Society of London'' and it has been in continuous publication ever since. It took its current name from the second volume, after the Astronomical Society of London became the Royal Astronomical Society (RAS). Until 1960 it carried the monthly notices of the RAS, at which time these were transferred to the newly established '' Quarterly Journal of the Royal Astronomical Society'' (1960–1996) and then to its successor journal ''Astronomy & Geophysics'' (since 1997). Until 1965, MNR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Piscium
Zeta Piscium (ζ Piscium, abbreviated Zet Psc, ζ Psc) is a quintuple star system in the zodiac constellation of Pisces. Based upon parallax measurements obtained during the Hipparcos mission, it is located roughly distant from the Sun. The system consists of a binary star (Zeta Piscium A) and a triple star system (BC), the latter consisting of a spectroscopic binary (B) and a single star (C). A's two components are themselves designated Zeta Piscium Aa (officially named Revati ) and Ab; B's two components as Ba and Bb. As the star system is 0.21° south of the ecliptic, it can be eclipsed ( occulted) by the moon, when close to or at one of its two nodes of its orbit; and is eclipsed by the sun from about 8-10 April. Nomenclature ''ζ Piscium'' ( Latinised to ''Zeta Piscium'') is the system's Bayer designation. The designations of the three constituents as ''Zeta Piscium A'', ''B'' and ''C'', and those of ''A's'' and ''B's'' components - ''Zeta Piscium Aa'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Piscium
Epsilon Piscium (Epsilon Psc, ε Piscium, ε Psc) is the Bayer designation for a star approximately away from the Earth, in the constellation Pisces. It is a yellow-orange star of the G9 III or K0 III spectral type, meaning it has a surface temperature around 5,000 kelvins. This is a normal giant star, slightly cooler in surface temperature, yet brighter and larger than the Sun. It is a suspected occultation double, with both stars having the same magnitude, separated by 0.25 arcsecond. Naming In Chinese, (), meaning '' Outer Fence'', refers to an asterism consisting of ε Piscium, δ Piscium, ζ Piscium, μ Piscium, ν Piscium, ξ Piscium and α Piscium. Consequently, the Chinese name for ε Piscium itself is (, en, the Second Star of Outer Fence.) In Japanese, 悠翔星 (Haruto-boshi), meaning "Soaring Forever Star," refers to the Japanese description of ε Piscium. Planetary system In 2021, a gas giant planetary candidate was de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Piscium
Delta Piscium (δ Piscium) is a solitary, orange-hued star in the zodiac constellation of Pisces. It has an apparent visual magnitude of +4.4, so it is bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 10.5 mas, it is around from the Sun. The visual magnitude of the star is diminished by an interstellar absorption factor of 0.08 due to interstellar dust. This is an evolved K-type giant star with a stellar classification of K4 IIIb. It has around 1.65 times the mass of the Sun and, at the age of three billion years, has expanded to 44 times the Sun's radius. The star is radiating 447 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,963 K. Because Delta Piscium is positioned near the ecliptic, so it is subject to lunar occultations. It has a magnitude 13.99 visual companion at an angular separation of 135.0 arc seconds on a position angle of 12°, as of 2011. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Piscium
Beta Piscium or β Piscium, formally named Fumalsamakah , is a blue-white hued star in the zodiac constellation of Pisces. Its apparent magnitude is 4.40, meaning it can be faintly seen with the naked eye. Based on parallax measurements taken during the Hipparcos mission, it is about 410 light-years (125 parsecs) distant from the Sun. Nomenclature ''β Piscium'' ( Latinised to ''Beta Piscium'') is the star's Bayer designation. It bore the traditional name ''Fum al Samakah'' from the Arabic فم السمكة ''fum al-samakah'' "mouth of the fish" (compare Fomalhaut). In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name ''Fumalsamakah'' for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning ''Thunderbolt'', refers to an asterism consisting of Beta Piscium and Gamma, Theta, Iota and Omega Piscium. Consequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Piscium
Alpha Piscium (α Piscium) is a binary star system in the equatorial constellation of Pisces. Based upon parallax measurements made by the Hipparcos spacecraft, it is about from the Solar System. The two components are designated Alpha Piscium A (officially named Alrescha, the traditional name of the system) and B. Nomenclature ''α Piscium'' ( Latinised to ''Alpha Piscium'') is the star's Bayer designation. The designations of the two components as ''Alpha Piscium A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). The system bore the traditional name ''Alrescha'' (alternatively ''Al Rescha'', ''Alrischa'', ''Alrisha'') derived from the Arabic الرشآء ''al-rishā’'' "the cord" and less commonly ''Kaitain'' and ''Okda'', the latter from the Arabic عقدة ''ʽuqdah'' "knot" (see Ukdah. In 2016, the International Astronomical Union ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called '' nutation''. In physics, there are two types of precession: torque-free and torque-induced. In astronomy, ''precession'' refers to any of several slow changes in an astronomical body's rotational or orbital parameters. An important example is the steady change in the orientation of the axis of rotation of the Earth, known as the precession of the equinoxes. Torque-free Torque-free precession implies that no external moment (torque) is applied to the body. In torque-free precession, the angular momentum is a constant, but the angular veloci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
