Visible at latitudes between +
90° and −
65°. Best visible at 21:00 (9 p.m.) during the month of November.
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, of similar size, to the southwest and
Aries, which is smaller, to the east. The
ecliptic and the
celestial equator intersect within this constellation and in
Virgo. This means the sun
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 Psc, and, due to
precession, slowly drifting due west, just below the western fish towards
Aquarius.
Although Pisces is a large constellation, there are only two stars brighter than magnitude 4 in Pisces. It is also the second dimmest of the zodiac constellations.
Note: magnitude, here, means apparent magnitude
Alrescha ("the cord"), otherwise
Alpha Piscium (α Psc), 309.8 lightyears, class A2, magnitude 3.62. Variable binary star.[1]
Fumalsamakah[2] ("mouth of the fish"), otherwise
Beta Piscium (β Psc), 492 lightyears, class B6Ve, magnitude 4.48
Delta Piscium (δ Psc), 305 lightyears, class K5III, magnitude 4.44. Like other stars near the ecliptic, Delta Piscium is subject to lunar occultations.[3]
Epsilon Piscium (ε Psc), 190 lightyears, class K0III, magnitude 4.27. Has a candidate exoplanet.[4]
Revati[2] ("rich"), otherwise
Zeta Piscium (ζ Psc), 148 lightyears, class A7IV, magnitude 5.21. Quintuple star system.[5]
Torcular ("thread"),[2] otherwise
Omicron Piscium (ο Psc), 258 lightyears, class K0III, magnitude 4.2. It is an evolved red giant star on the
horizontal branch.[8]
Gamma Piscium (γ Psc), 138 lightyears, magnitude 3.70. The star hosts an
exoplanet which was discovered in 2021.[4] It has a spectral type of G8 III.[11]
Van Maanen's Star is the closest-known solitary white dwarf to us, with a dim apparent magnitude. It is located about 2° to the south of the star
Delta Piscium,[12] with a relatively high
proper motion of 2.978″ annually along a
position angle of 155.538°.[13] It is closer to the Sun than any other solitary white dwarf. It is too faint to be seen with the
naked eye.[12] Like other white dwarfs, it is a very dense star: its mass has been estimated to be about 67% of the
Sun's,[14] yet it has only 1% of the
Sun's radius.[15] The
outer atmosphere has a temperature of approximately 6,110
K,[14] which is relatively cool for a white dwarf. As all
white dwarfs steadily radiate away their heat over time, this temperature can be used to estimate its age, thought to be around 3 billion years.[16] It was originally thought to be an
F-type star before the properties of white dwarfs were known.[17][18]
Due to the dimness of these stars, the constellation is essentially invisible in or near any major city due to
light pollution.
Deep-sky objects
M74 is a loosely wound (type Sc)
spiral galaxy in Pisces, found at a distance of 30 million light years (
redshift 0.0022). It has many clusters of young stars and the associated
nebulae, showing extensive regions of
star formation. It was discovered by
Pierre Méchain, a French astronomer, in 1780. A
type II-P supernova was discovered in the outer regions of M74 by
Robert Evans in June 2003; the star that underwent the supernova was later identified as a
red supergiant with a mass of 8
solar masses.[19] It is the brightest member of the
M74 Group.[20][21][22]
NGC 488 is an isolated face-on prototypical spiral galaxy.[23] Two supernovae have been observed in the galaxy.[24]
NGC 520 is a pair of colliding galaxies located 105 million light-years away.[25]
CL 0024+1654 is a massive
galaxy cluster that
lenses the galaxy behind it, creating arc-shaped images of the background galaxy. The cluster is primarily made up of yellow
elliptical and spiral galaxies, at a distance of 3.6 billion light-years from Earth (redshift 0.4), half as far away as the background galaxy, which is at a distance of 5.7 billion light-years (redshift 1.67).[19]
History and mythology
Pisces originates from some composition of the
Babylonian constellationsŠinunutu4 "the great swallow" in current western Pisces, and Anunitum the "Lady of the Heaven" (supposedly
Inanna), at the place of the northern fish. In the first-millennium BC texts known as the Astronomical Diaries, part of the constellation was also called DU.NU.NU (Rikis-nu.mi, "the fish cord or ribbon").[26]
Greco-Roman period
Pisces is associated with the Greek legend that
Aphrodite and her son
Eros either shape-shifted into forms of fishes to escape, or were rescued by two fishes.
In the Greek version according to
Hyginus, Aphrodite and Eros while visiting
Syria fled from the monster
Typhon by leaping into the
Euphrates River and transforming into fishes (Poeticon astronomicon 2.30, citing Diognetus Erythraeus).[27] The Roman variant of the story has
Venus and
Cupid (counterparts for Aphrodite and Eros) carried away from this danger on the backs of two fishes (
OvidFasti 2.457ff).[28][29]
There is also a different origin tale that Hyginus preserved in another work. According to this, an egg rolled into the Euphrates, and some fishes nudged this to shore, after which the doves sat on the egg until Aphrodite (thereafter called the
Syrian Goddess) hatched out of it. The fishes were then rewarded by being placed in the skies as a constellation (Fabulae 197).[30][31] This story is also recorded by the
Third Vatican Mythographer.[32]
Modern period
In 1690, the astronomer
Johannes Hevelius in his Firmamentum Sobiescianum regarded the constellation Pisces as being composed of four subdivisions:[33]
"
Piscis Austrinus" more often refers to a separate constellation in its own right.
In 1754, the botanist and author
John Hill proposed to sever a southern zone of Pisces as Testudo (the Turtle).[34] 24 – 27 – YY(30) – 33 – 29 Psc.,[35] It would host a natural but quite faint
asterism in which the star 20 Psc is the head of the turtle. While
Admiral Smyth mentioned the proposal,[36] it was largely neglected by other astronomers, and it is now
obsolete.[35]
Western folklore
The Fishes are in the German lore of Antenteh, who owned just a tub and a crude cabin when he met two magical fish. They offered him a wish, which he refused. However, his wife begged him to return to the fish and ask for a beautifully furnished home. This wish was granted, but her desires were not satisfied. She then asked to be a queen and have a palace, but when she asked to become a goddess, the fish became angry and took the palace and home, leaving the couple with the tub and cabin once again. The tub is sometimes recognized as the
Great Square of Pegasus.[37]
In non-Western astronomy
The stars of Pisces were incorporated into several constellations in
Chinese astronomy. Wai-ping ("Outer Enclosure") was a fence that kept a pig farmer from falling into the marshes and kept the pigs where they belonged. It was represented by Alpha, Delta, Epsilon, Zeta, Mu, Nu, and Xi Piscium. The marshes were represented by the four stars designated Phi Ceti. The northern fish of Pisces was a part of the House of the Sandal, Koui-siou.[38]
^Wraight, K. T.; Fossati, L.; Netopil, M.; Paunzen, E.; Rode-Paunzen, M.; Bewsher, D.; Norton, A. J.; White, Glenn J. (2012). "A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars". Monthly Notices of the Royal Astronomical Society. 420 (1): 757.
arXiv:1110.6283.
Bibcode:
2012MNRAS.420..757W.
doi:
10.1111/j.1365-2966.2011.20090.x.
S2CID14811051.
^Meyer, C.; et al. (1995), "Observations of lunar occultations at Observatoire de la Cote d'Azur", Astronomy and Astrophysics Supplement, 110: 107,
Bibcode:
1995A&AS..110..107M.
^
abTeng, Huan-Yu; Sato, Bun'ei; Takarada, Takuya; Omiya, Masashi; Harakawa, Hiroki; Izumiura, Hideyuki; Kambe, Eiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro (2022), "Regular radial velocity variations in nine G- and K-type giant stars: Eight planets and one planet candidate", Publications of the Astronomical Society of Japan, 74: 92–127,
arXiv:2112.07169,
doi:
10.1093/pasj/psab112
^Aurière, M.; Konstantinova-Antova, R.; Charbonnel, C.; Wade, G. A.; Tsvetkova, S.; Petit, P.; Dintrans, B.; Drake, N. A.; Decressin, T.; Lagarde, N.; Donati, J. F.; Roudier, T.; Lignières, F.; Schröder, K. P.; Landstreet, J. D.; Lèbre, A.; Weiss, W. W.; Zahn, J. P. (February 2015), "The magnetic fields at the surface of active single G-K giants", Astronomy & Astrophysics, 574: 30,
arXiv:1411.6230,
Bibcode:
2015A&A...574A..90A,
doi:
10.1051/0004-6361/201424579,
S2CID118504829, A90.
^Griffin, R. F.; Redman, R. O. (1960), "Photoelectric measurements of the λ4200 A CN band and the G band in G8-K5 spectra", Monthly Notices of the Royal Astronomical Society, 120 (4): 287–316,
Bibcode:
1960MNRAS.120..287G,
doi:10.1093/mnras/120.4.287.
^van Maanen, A. (December 1917), "Two Faint Stars with Large Proper Motion", Publications of the Astronomical Society of the Pacific, 29 (172): 258–259,
Bibcode:
1917PASP...29..258V,
doi:10.1086/122654.
^
ab
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