Constellations: Pisces 'the Fish' Content from the guide to life, the universe and everything

Constellations: Pisces 'the Fish'

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The shield of the Science, Mathematics and Engineering faculty of the h2g2 University.Constellations: Overview | Andromeda | Antlia | Apus | Aquarius | Aquila | Ara | Aries | Auriga | Boötes | Caelum
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The Chinese I-Ching character K'AN (fathomless water) and two circling fish.
Taking the five loaves and the two fish and looking up to Heaven, Jesus gave thanks and broke the loaves. Then he gave them to his disciples to set before the people. He also divided the two fish among them all. They all ate and were satisfied, and the disciples picked up twelve basketfuls of broken pieces of bread and fish. The number of men who had eaten was five thousand.
- Mark 6:41-44

Pisces the Constellation

Name:Pisces (Latin 'fish')
Genitive:Piscium
Short form:Psc
Area:889 sq deg
Co-ordinates1:Right Ascension 01h, Declination +15°
Zodiac:Yes
Origin:Ancient

Pisces shares its borders with Andromeda, Pegasus, Aquarius, Cetus, Aries and Triangulum. Quite a substantial size, Pisces ranks 14th of the modern 88 internationally recognised constellations. It's supposed to represent two fish joined at their tails, but tracing the stars from the asterism known as 'The Circlet' you end up with a snake-like creature bent in the middle. The bend is to the alpha star, Alrescha; this and a few others are below the ecliptic.

Due to its positioning bordering the ecliptic, Pisces is a member of the zodiac and an astrological sign, sometimes playing host to the planets, the Moon and the Sun.

Pisces is distinguishable because it contains the Vernal Equinox, the point where the Sun appears to cross the celestial equator into the northern hemisphere every year. Some people know this date as the first day of Spring. The gradual shift of the Earth on its axis is called precession, a 26,000 year wobble as the Earth rotates, and this has caused the Vernal Equinox to move into Pisces. Between 1500 BC and 500 BC the Vernal Equinox was in Aries.

Surprisingly, given its generous portion of the sky, there is just one Messier object, M74, which is a fabulous clockwise spiral galaxy around 32 million light years2 distant. Then there's the mindboggling Perseus-Pisces Supercluster of galaxies over 220 million light years away, which measures 300 million light years across.

Mythology

One story of the origin of Pisces the fish constellation concerns the gods of Olympus themselves. The god Typhon was a fearsome monster who all the other gods fled from when he stormed Mount Olympus. Even the mighty Zeus, who had morphed into the form of a ram, could not escape and he was imprisoned by Typhon. The goddess of love, Aphrodite (Venus) and her son Eros (Cupid) had transformed themselves into fish to swim to safety up the River Nile. Typhon was eventually defeated when Zeus trapped him by dropping Mount Etna on him. Being immortal, the god Typhon could not die, so he remains trapped beneath the earth, erupting when disturbed. The two fish were placed in the night sky as a reminder against complacency.

Stars

The scientific star names are simple to understand (if you know your Greek alphabet). For example: the 'alpha' star means that it is the brightest star in that constellation. The next brightest is designated 'beta', etc. Combined with the genitive name, this is known as the 'Bayer designation'. Some stars have proper names as well, for example, alpha Piscium is Alrescha. Other stars are known by their catalogue number.

That's the way it's supposed to work, but sometimes the measurements were a little off, or the stars are variable. In this case, the brightest star of Pisces is the eta designated star which is magnitude +3.6, followed closely by the gamma star, with the next brightest star the rather bizarrely designated omega. Omega is the last letter of the Greek alphabet and as such, the omega star should be the least bright of the whole constellation; in fact some constellations don't even reach an omega designation because there aren't that many stars in them! The iota star ranks behind the omega, then comes omicron, epsilon and theta before the alpha star, Alrescha, finally gets a look-in. The stars in the table are listed in order of brightness.

Star Table

StarDesignationName or
catalogue number
MagnitudeDistance
(light years)
Spectral classification
and/or comments
η Psceta Piscium99 Piscium+3.6294Yellow giant
γ Pscgamma Piscium6 Piscium+3.69 var126Yellow giant
ω Pscomega Piscium28 Piscium+4.04104Yellow-white dwarf
ι Psciota Piscium17 Piscium+4.13 var41Yellow-white dwarf
ο Pscomicron Piscium110 Piscium+4.26 var142Yellow dwarf
ε Pscepsilon Piscium71 Piscium+4.28 var199Yellow dwarf
θ Psctheta Piscium10 Piscium+4.28 var165Orange giant
α Pscalpha PisciumAlrescha+4.3 var139Binary star system
δ Pscdelta Piscium63 Piscium+4.44305Orange giant
ν Pscnu Piscium106 Piscium+4.45 var368Orange giant
β Pscbeta PisciumFum al Samakah+4.48 var492Blue-white dwarf
λ Psclambda Piscium18 Piscium+4.5 var104White dwarf
τ Psctau PisciumAnunitum+4.5162Orange dwarf
φ Pscphi Piscium85 Piscium+4.6 var377Binary star system
ξ Pscxi Piscium111 Piscium+4.6191Orange giant
υ Pscupsilon Piscium90 Piscium+4.7 var311White dwarf
μ Pscmu Piscium98 Piscium+4.8 var360Multiple star system
κ Psckappa Piscium8 Piscium+4.95 var162Multiple star system
ζ Psczeta Piscium86 Piscium+5.2148Binary star system
π Pscpi Piscium102 Piscium+5.5110Yellow-white dwarf

New General Catalogue (NGC)

The NGC was compiled by John Louis Emil Dreyer (the director of the Armagh Observatory from 1882 to 1916).

Galaxies

Galaxies are categorised by their shape:

  • Spirals have 'arms' which rotate either clockwise (CW) or anti-clockwise (ACW) and they may have a central bar.
  • Elliptical galaxies have no arms and are usually shaped like rugby balls.
  • Lenticular galaxies are a mix between spiral and elliptical.
  • Seyfert galaxies, named after their discoverer, American astronomer Carl Seyfert, have active black holes at their core.
  • Interacting galaxies have an effect upon each others' gravity. This can result in the cannibalisation of a smaller one, or a cosmic trainwreck.

NGC Table

CatalogueTypeMagnitudeDistance
(million light years)
Remarks
NGC 100Spiral galaxy+14.641Edge-on
NGC 266ACW spiral galaxy+1399Barred
NGC 382Elliptical galaxy+14.2230Supernova 2000dk
NGC 383Lenticular galaxy+12230Pisces cluster
NGC 474Elliptical galaxy+12100Interacting with
nearby galaxies
NGC 488CW spiral galaxy+10.395Pisces cluster
NGC 507Elliptical galaxy+13225Interacting with NGC 508
NGC 508Lenticular galaxy+14.5225Interacting with NGC 507
NGC 514ACW spiral galaxy+12105Pisces cluster
NGC 520Starburst galaxy+12100Mid-range Merger
NGC 524Elliptical galaxy+10.6225Supernova 2000cx
NGC 660Seyfert galaxy+15.524Post-merger/Polar ring

Meteor Showers

Meteor showers occur when the Earth passes through the debris path left by the tail of a comet. There are a couple of meteor showers which appear to hail from Pisces, the Gamma Piscids during October, and the Upsilon Piscids of May. Neither of the events have had any spectacular shows recorded, the best ZHR (Zenithal Hourly Rate) so far is eight, with the maximum count recorded over one whole evening (six hours) being 17.

Extrasolar Planets in Pisces

Over 2,000 years ago the Greek philosophers Aristotle and Epicurus argued about whether there were other Earth-like planets orbiting distant suns. There have been several extrasolar planetary systems found in the constellation Pisces up to 2008; the first was discovered in 1998. One star, HD 217107, has at least two planets orbiting it that we know of. HD 3651 is a yellow dwarf 36 light-years distant. In 2003 a brown dwarf (failed star) HD 3651 B and a planet HD 3651 b were discovered in orbit around it.

Figures given in the table below are the length of the planet's orbital period around its parent star, which we know of as a year. The mass of the extrasolar planet is compared to that of Jupiter, our Solar System's largest planet, known by astronomers as the 'Jovian scale'.

Extrasolar Planets Table

Star name or
catalogue number
Planet
catalogue number
Planet mass
(Jovian scale)
Orbital period
(Earth days)
Year of discoveryComments
109 Piscium109 Piscium b6.81,0762000Superjovian
HD 4203HD 4203 b1.654012001Gas giant
HD 4203HD 4203 c2.176,7002014Gas giant
HD 8574HD 8574 b2.22282002Gas giant
54 Piscium A54 Piscium A b0.23622003Hot sub-jovian
HD 217107HD 217107 b1.377.131998Hot Jupiter
HD 217107HD 217107 c2.53,3002005Gas giant
HD 3651HD 3651 b0.2622003Hot gas giant
WASP-28WASP-28 b0.93.42010Hot gas giant
WASP-32WASP-32 b3.62.722010Hot superjovian
HD 4313HD 4313 b2.33562010Superjovian
HD 217786HD 217786 b131,3192010Possible brown dwarf
HD 218566HD 218566 b0.21225.72010Sub-Saturn, possible habitable zone
HD 5891HD 5891 b7.61772011Superjovian
HD 1502HD 1502 b3.14322011Superjovian
WASP-76WASP-76 b0.91.812013Hot gas giant
HAT-P-51HAT-P-51 b0.34.22015Hot gas giant
HD 12484HD 12484 b358.82016Hot superjovian
HD 3167HD 3167 b0.0160.962016Hot super-Earth
HD 3167HD 3167 c0.03302016Hot super-Earth
WASP-118WASP-118 b0.54.052016Hot gas giant
HD 3167HD 3167 d0.0228.52017Hot super-Earth

Down to Earth

Astrology

Pisces is the 12th sign of the zodiac3 and astrologers today still use dates which are over 2,000 years out of date. So newspaper and magazine columnists say that Pisces covers the dates between 19 February and 20 March. However, currently (2008) the sun occupies Pisces between 15 March and 13 April.

If you believe in such things, the Piscean zodiacal sign has Neptune as its ruling planet, white as its characteristic colour and chrysotile as its lucky jewel. Subjects of Pisces are said to be altruistic, highly sensitive and given to extremes of elation and depression.

Some famous Piscean people are: Douglas Adams (author); Alexander Graham Bell (telephone inventor); Albert Einstein (physicist); Yuri Gagarin (pioneering astronaut); George Harrison (musician); Sir Patrick Moore (astronomer/TV presenter); Samuel Pepys (diarist).

Folklore

According to medieval tradition, the constellation of Pisces was associated by ancient Babylonian or Persian Magi4 with the nation of Israel. This led the German astronomer Johannes Kepler to consider it as the likely location of the Star of Bethlehem.

Pisces in Modern Culture

  • Pisces Iscariot is an album by The Smashing Pumpkins.
  • In the Dune universe of Frank Herbert, the Imperial House Corrino hail from the gamma star system of Pisces.

and Finally ...

Pisces Halcyon is a British author, poet and artist.

1Current IAU guidelines use a plus sign (+) for northern constellations and a minus sign (−) for southern ones.2A light year is the distance light travels in one year, roughly 5.88 trillion miles or 9.46 trillion km.3If you look at the ecliptic on a star map the Sun actually passes through 13 constellations, the 12 'star signs' that most astrology devotees know, plus Ophiuchus 'the Serpent Bearer'. Possibly the actual number is considered too unlucky to be considered for an update.4Astronomers or 'wise men'.

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