As everyone knows, Aquarius is a zodiacal constellation, since the Sun passes within its boundaries during its annual journey. Before proceeding, let me make a not purely astronomical note: the name I use, Aquarius, comes from the Latin word Aquarius, while in Italian it should be written Aquarius: let's leave this last handwriting for nice furnishing objects of our houses or scientific institutions, in both cases teeming with marine fauna and flora. As we will see shortly, the Aquarius in question is really quite different.
Aquarius is crossed by the ecliptic (the apparent path of the Sun through constellations that from this are called zodiacal) and our diurnal star lingers in those zones of the sky between February 17th and March 12th (two variable dates from year to year because of the perturbed motion of the Earth around the Sun and because of the precession): obviously there is no correspondence between these dates and those that horoscopes or other such amenities offer us.
Among my memories there's a nice song taken from the musical "Hair" of the late '60s, called "Aquarius" and in which it talks about Moon, Jupiter and Mars and a questionable dawning of the age of Aquarius, on which I don't add anything else, because it's definitely off-topic: at least it's a cheerful little tune that maybe the younger ones don't even know.
Returning to a consolidated tradition every time I speak of zodiacal constellations, I remember that more or less in the period in which the song was heard, the state of San Marino issued a series of stamps on an astronomical theme of 12 values, obviously expressed in Lire: the Aquarius was entitled to the second highest value (since after him there are only Pisces, starting from 1 lire for Aries), those 100 lire that at the time were certainly not worth little.
The name, the history, the myth of Aquarius
The constellation Aquarius is a zodiacal constellation and represents a young man pouring water into the mouth of the nearby Southern Fish.
Its mythological connotation is quite uncertain, however, Aquarius is one of the most ancient constellations, originally from Mesopotamian culture. It is linked to the Sumerian god En-ki (lord of the earth), who later became Ea, god of water and wisdom in the culture of the Akkadians and Babylonians. Initially represented as a man with a fish body or whose body is covered by a fish skin, Ea appears in some depictions at the top of a hill and from his shoulders or from the water bottles supporting him, two streams of water come out and pour into the mouth of a fish, often identified as the Southern Fish. In the two jets are sometimes identified the two rivers of the Mesopotamian region, the Tigris and the Euphrates, which, in different representations, do not pour into the mouth of a fish, but appear full of fish. Ideler, a German astronomer, explains this representation by the fact that the Sun was in that portion of the sky during the rainy season. In fact, the asterism must have originated around 1700 BC when the Sun entered Aquarius in January.
The myth linked to the most famous Aquarius, quoted not only by the Greek authors but also by the Latins, has as protagonist Ganymede, an adolescent belonging to the royal lineage of Troy, son of King Troo, founder of Troy and Dardania and Calliroe, one of the Naiads.Fascinated by its beauty, Zeus fell madly in love with it, took the form of the Eagle and caught it while it was grazing the flock on the slopes of Mount Ida, and kidnapped it. He took him to Olympus and made him his lover. Zeus elected him cupbearer of the gods. According to Ovid, Ganymede poured clear water and nectar into the cups of the gods and that of Zeus (Fasti, dies -1 AD).
The Water Carrier
This is obviously the meaning of the term Aquarius, which I was talking about at the beginning: certainly not a tank containing fish, but a young man carrying water, which has always been a very precious and indispensable good. In all three versions, the two ancient and the modern one, you can see the aquarium at the end of its journey, in the act of pouring the precious contents of its amphora. According to Hevelius we see a little boy barely covered by a band of cloth
while in the Uranometria the little boy has definitely grown, just as the cloth that (let's say so) covers him has grown
Stellarium instead shows the young man from the front, decidedly more covered, curved under the weight of the jug actually not really big
Inside the constellation of Aquarius we find three stars close to our Solar System: the nearest one is the star Luyten 789-6 (EZ Aqr) placed at a distance of 11.4 light years from us. Thanks to Celestia, we can immediately see how our Sun appears to the eyes (in this case four) of our friends Ezaquari: our yellow dwarf appears of magnitude 2.5, therefore not very bright, placed practically inside our Leo, with an excellent intruder, α Centauri, which is in those parts for the usual game of three-dimensional perspectives, of which we realize thinking every single star in its spatial location in three coordinates, something that Celestia does very well.
This star is in reality multiple and always thanks to Celestia we can see the various components from a certain distance, in order to frame them all together.
The second nearest star to us is the GI 876 (IL Aqr), located 15.3 light years away, from which our Sun is located in the same area of the sky, so I have not bothered the dear Gliaquari: you must know that they are all precise types, starting from their name, which was originally Ilaquari, modified by means of a referendum, given the blatant grammatization that caused them many headaches (I forgot to tell you that they have two).
The third star in order of distance is instead Gliese 849 (HIP 109388), located 29 light years from Earth: this time a visit to our friends Gliesippi was a must (especially to taste their famous bean juice, for which they are known all over the cosmos), to confirm that at that distance our poor Sun shines (so to speak) almost of fifth magnitude, while now the panorama has slightly changed, due to the three-dimensional presence of another excellent stellar neighbor of ours, as his majesty Sirius, much weaker, with a magnitude equal to 1.6.
A few big stars
Aquarius is home to about ten stars larger than 50 times our small Sun: in the table we can see the value of the ray with respect to the Sun, the name of the star, with in the first three cases the link to the photo taken with Celestia of the star seen by 10 UA and finally the spectral class of the star.
In the usual diagram made by me we can see, beyond the pure figures, the comparison between the size and the spectral class of these stars and that of other stars that we have met in the previous articles: as always we see that decidedly little known stars, like the first 4 of the list, overhang very famous stars like the usual Rigel and Aldebaran, while the Sun is always there, little visible, reduced to a dot.
I would like to underline an issue concerning the name of the third star in the ranking (k Aqr, also known as 63 Aqr): the letter "k" indicated here is precisely the letter "k" of the Latin alphabet, according to what is Bayer's Nomenclature (that of Uranometry) "extended" which provides, for the identification of stars, first the letters of the Greek alphabet and then the Latin ones, then the capital letters from A to Q (since from R onwards are used for variable stars). It's the first time that it happens to talk about this topic and in particular about conflict between pairs of stars, just because the star in question is not the star κ Aqr where this time "κ" is the Greek letter, (also known as 3 Aqr), completely different, so much so that it is of class K2 and also received the name Situla. Potentially in every constellation there could be this homophony between names of two stars (the spelling of the symbol is really little different, "k" instead of "κ"), but in reality it occurs only with extended constellations rich of many stars catalogued also in the past. For the record there is also the Nomenclature of Flamsteed, an alternative to the previous one, which provides for the use of numbers followed by the initials of the constellation.
In later times and especially recently, various star catalogues have been created, usually "thematic" (for example the Gliese of the nearby stars), which group stars having certain common characteristics: among the most famous is the HIP catalogue (mainly built with the precious data of the Hipparcos probe) containing stars having a parallax above a certain threshold. The flourishing of this impressive and important series of specialized star catalogues, means that a star has at least 5-6 different denominations, to which the possible proper name must be added, precisely because this star has characteristics that place it in certain catalogues rather than others.
An example, taken from the very famous astronomical database SIMBAD, reports for the star χ Aqr, the beauty of 27 different names, while a more famous star like Sirius, of different names, has 58 (here we can see them all).
Deep sky objects
Inside the constellation of the Aquarium there are many beautiful Deep Sky objects, which we will now see in the fantastic photos made by the Hubble Space Telescope: as always clicking on the single photo you get a high definition version. Let's start from a stunning globular cluster, catalogued in second place by Messier (M2)
the globular cluster M2
Always in the same catalogue, we find a fantastic cluster of stars of different colours, M72
the globular cluster M72
while in the next place in Messier's catalogue (M73) we find an open cluster definitely less rich in stars
star cluster M73
Among the nebulae we find in this constellation the famous Saturn Nebula (NGC 7009), which received this name because observing it with not very powerful instruments can be mistaken for the well known planet
but thanks to this photo we see that the resemblance to the planet of the rings has practically disappeared.
Let's close the gallery of images with another well known planetary nebula, the Helix Nebula (NGC 7293) also this one worthy to be placed as wallpaper in our PC.
The names of the stars of Aquarius
Our water carrier has a number of stars with a proper name:
- Sadalmelik (α Aqr): from Arabic, the lucky king
- Sadalsuud (β Aqr): the luckiest of the lucky ones
- Sadachbia (γ Aqr): the lucky star of hidden things.
- Skat (δ Aqr): the tibia
- Albali (ε Aqr): the good luck of the eaters
- Alsad (ζ1 and ζ2 Aqr): the lucky one
- Ancha (θ Aqr): the hip
- Situla (k Aqr): the bucket
- Hydor (λ Aqr): from Greek, water
- Albulan I and II (μ and ν Aqr): the eaters
- Seat (π Aqr) the lucky man's tent
The visibility of the Aquarium
The constellation Aquarius is very large, so I will consider only the central part: at 9 p.m. it lies low on the eastern horizon at the beginning of August, culminating in the south at the beginning of November, while it lies low in the west in the following New Year's Eve.