In this episode we will get to know better another zodiacal constellation, first of all looking for it in the sky: it has to be said that, if you can observe it from a position far from the lights, you can easily recognize it without too much effort of imagination. We are in the presence of two fish strangely connected by a sinuous string to a point, the star α Psc. Since I remember immediately that the abbreviation reads "Piscium", plural genitive of Pisces. From the figure obtained as always thanks to Stellarium, we see a sort of "V" shaped string with two strange figures attached at the bottom (a triangle and a pentagon) that should represent two fishes. We don't complain too much because, as we have already seen many times, some constellations can't be recognized at all...
The one of Pisces is a constellation of the Zodiac, the last one, and therefore we expect the Sun to travel it during its annual motion on the celestial sphere, along that imaginary line called ecliptic: in the figure we see it drawn in red almost cutting the constellation in two parts, between March 12 and April 18. Once again I want to underline the complete disagreement of these dates with those published on newspapers and magazines in horoscopes: I remember that the latter "travel on their own" and have absolutely nothing to do with the Sun and its position among the constellations. Instead, as always from year to year, the two dates of entry and exit can vary little because of the irregular motion of the Earth around the Sun: being us on Earth, it is obvious to attribute this irregularity to the Sun, as if it were the Sun moving abnormally between the constellations!
As many others known so far, that of Pisces is a strange constellation, not so much because it does not present particularly bright stars, but because for example the brightest (with a magnitude equal to 3.6) is the star η Psc (Alpherg), slightly brighter than the already mentioned α Psc (Al Rescha), while the star β Psc (Fum al Samakah) is not even part of the figure that traditionally identifies it.
With the cut sheet and the distances lit we see that in this constellation there are three stars quite close to the Sun: they are 107 Psc, 54 Psc and ι Psc, respectively 25, 36 and 45 light years away from the Sun.
But even closer to the Sun is a 14-year-old dwarf, a white dwarf placed just 14 light years away from us: it is the so-called Van Maanen Star, named after the Danish-American discoverer who studied it in depth.
The name, the history, the myth
In Christian culture Pisces are identified with Christ, the "first fish", born after the point of the spring equinox had passed from Aries into Pisces marking the passage to the new "Great Age".
It seems that the ancient form of Pisces consisted of one fish. According to the Greek astronomer Eratosthenes (born in 276 BC), the origin of the symbolism of the fish should be sought in Derke, a Syrian deity half fish and half woman. The myth is also told by Ovid, in the Fasti. In fact, the Romans brought together the idea of the fish goddess in their myth of Cupid and his mother Venus (Eros and Aphrodite, Greek). Euphrates' banks: in order to escape from the monster Typhon, born of Gaea, personification of the impetuous south wind that had attacked them, Venus grabbed Cupid and plunged into the sea, where they both changed into fish. To make sure they did not get lost, they tied each other with a rope, as they are remembered in heaven. In the end it was Jupiter who defeated the monster, but the fish were still destined for heaven.
Just to go and see what the sky looked like near the Sun, I climbed on my well-known virtual spaceship (the Celestia program) to visit my hundred-seventeen colleagues, one of whom writes articles on their most beautiful website. The Sun appears as a fourth star in the midst of other not very bright stars, between the Raven and the Hydra, with a little more distant the well known Sirius, from here a little more brilliant than the first one.
In a jiffy I went to say goodbye to my very nice and cordial friends fifty-four children: it is no coincidence that they are called this way, since on their planet a miraculous water gushes out that makes them stay young for a long time. The only side effect is that they always talk about cartoons, video games and dolls and you can't deal with more serious topics such as the famous "PLP effect". Going back to their skies, there is not much to add compared to the previous picture, except that the Sun is now fifth .
The third star I visited is the one around which the Iotapisci revolve, really unpleasant characters, always snouts: and yet theirs is a little star of class F7, a little bigger and whitish than our Sun. Maybe they resent what we call them, but we can't do anything about it! Even from here the Sun is quite disappointing, being 5.5 and therefore visible only on nights when their five moons are below the horizon.
Last but not least, here I am arrived by my Vanmaanenian friends, where our star is 3 and therefore visible to the naked eye, surrounded by stars of the constellation of Virgo, with an excellent intruder (α Cen) that precisely because of its proximity to the Sun is in the most unlikely places in the sky, if observed by other stars nearby.
Let's compare the stars
Analyzing the size of the stars belonging to the constellation of Pisces, in data bases that can be found a bit here and a bit there in specialized sites, we find the presence of as many as 5 stars with a physical size greater than 50 times our Sun. From the figure on the side, realized as always by the undersigned, we see that these stars are few but good: the biggest is the giant 19 Psc, class C and almost 300 times bigger than our Sun! The second in the ranking, 57 Psc is another little monster, a red M class, 140 times bigger than our yellow dwarf. The other three biggest stars are 30, 47 and h Psc, the first two of class M and therefore red, while the last one is class G6, a big sister of our Sun: they are 97x, 89x and 59x respectively, always victorious in comparison with the famous Aldebaran and able to compete with the bright Rigel.
Precisely because of its enormous size, 19 Psc deserves a trip up to a safe distance: if we position ourselves at 10 astronomical units (practically the distance between Saturn and the Sun), we see this stellar monster shining an annoying red light and occupying 13° of the sky. If we think that our bright Sun has a diameter of just half a degree, we can immediately get an idea of its monstrosity: it appears more than 25 times bigger than the Sun, if seen from the enormous distance of 10 UA.
Representations of Pisces
Let's now see how this constellation was depicted in antiquity and how it is seen modernly. In Bayer's Uranometry it was depicted as follows
Recently, but we are still talking about the 70s, the Post Office of the Republic of San Marino had issued a series of 12 stamps depicting the constellations of the zodiac: since the nominal values were increasing compared to the natural order of the constellations, Pisces had been assigned the highest value, equal to 180 lire, which could be used in the case of large and bulky mail packages... Other times indeed!
Astronomer Hevelius depicted her mirroring her in this way
and finally Stellarium shows it this way
A simply perfect galaxy
Within this constellation we find a galaxy that has not wrongly been renamed the "perfect spiral galaxy". Looking at this exceptional photo by the Hubble Space Telescope (in high resolution if we click on the photo) we can only give reason to the inventor of this appellation!
- Al Rescha (α Psc): Arabic word meaning twine
- Fum al Samakah (β Psc): Arabic word that means the mouth of the fish
- Linteum (δ Psc): Latin word meaning canvas, found in internet
- Kaht (ε Psc): word of unknown meaning (it would seem Klingonian), found in internet
- Kuton I, II and III (δ, ζ1 and ζ2 Psc): word meaning twine
- Alpherg (η Psc): from Arabic, the home of the fish
- Torcular (ο Psc): from Latin, (guess what) the thread
- Vernalis (ω Psc): Latin word meaning spring, found on the internet, almost certainly because it is located near the Vernalis Point, where the Sun is on March 21, in the spring equinox.
Always searching on the internet I found, in fact, the star called Linteum (δ Psc) that will become very famous (you can bet!) because it will be hidden by the Moon on December 21 of this year. Does this date remind you of anything?