XI. sign of zodiac
One of the constellations of the Zodiacal
Constellation Family. The sun passes through this constellation from mid
February to mid March.
Aquarius streches from the celestial equator to the southern hemisphere: RA=20h40m to RA=0h and DECL=3 degrees to DECL=-24 degrees respectively. It is surrounded by Pegasus Equuleus and Delphinus at the northern border, Aquila to the west, Capricornus at the south-western border, Piscis Austrinus and Sculptor to the south, Cetus to the east and finally Pisces at the north-eastern edge.
The stars gamma Aqr (called Sadachbia), eta Aqr, zeta Aqr and pi Aqr form a small, Y-shaped asterism which is a characteristic feature for this constellation. It is thought to mark the water jar of Aquarius.
Stars and other objects
The double zeta Aqr consists of a tight pair of F stars (F6IV and F3V).
Both components are nearly of equal brightness showing 4.59 mag and 4.42 mag.
To separate the stars are telescope with an aperture of at least 75mm is
The pair of a 15176 is also tight. The two stars revolve each other every 71 years. To split this double into its components scopes with an aperture of about 20mm are needed.
To the star group M 73 belong four stars forming an asterism. Three of the stars are of 11th magnitude, the fourth is even weaker, of 12th magnitude. They look like a tiny nebulosity which is why they were included to the Messier catalog.
The globular cluster M 72 is less concentrated towards its center than many other globular cluster. Viewed with small scopes it is not very impressive.
Even without optical help the globular cluster M 2 can be seen. It is one of the richer clusters. Small scopes and binoculars show a misty patch with a concentration towards its center.
NGC7009 belongs to the brightest planetary nebulae. For it resemblance with the planet Saturn it is called Saturn Nebula: in larger scopes it appears as a bright inner ring surrounded by a patchy disk. Small scopes show a misty greenish disk of 8th mag.
With a distance of just about 600 lightyears the planetary nebula NGC 7293, known as the Helix Nebula, is the closest of all planetaries. Its apparent diameter is about the half of the moon. It is best viewed through binoculars or telescopes at small magnifications. Then it appears as a circular hazy patch. To see it in its full beauty long-exposure photographs are necessary revealing two overlapping loops of gas.
The meteor shower of the March Aquarids belong to the daylight showers. It was first detected 1961 by C. S. Nilsson. With radar methods the shower activity could be traced from March 11th to March 16. The might be a connection to the Northern Iota Aquarids.
The Southern Iota Aquarids fall from July 1st to September 18th. The maximum occurs on August 6th with an hourly rate of 7-8 meteors. The Northern Iota Aquarids occur during August 11th to September 10th. Maximum occurs on August 25th, at which time 5-10 meteors per hour can be seen. Both streams produce meteors with an average magnitude slightly fainter than 3.
The shower of the Delta Aquarids also shows two distinct showers. The Southern Delta Aquarids have a duration from July 14th to August 18th with a maximum hourly rate of 15-20 on July 29th. The duration of the Northern Delta Aquarids extends from July 16th to September 10th. The maximum occurs on August 13th with a high of 10 metoers per hour.
Finally the shower of the Eta Aquarids is visible during the period of April 21th to May 12th. It reaches maximum on May 5th when the hourly rates usually reach 20 for observers in the northern hemisphere and 50 for observers in the southern hemisphere.
The antique sources differ in the interpretation of this constellation.
Eratosthenes of Cyrene (230 B.C.) stated in his Catasterismi (26) that Aquarius was Ganymedes when serving wine or nectar to Zeus.
Hygenus was of the opinion that Aquarius represented Deukalion and the water he pours stood for the Flood (poeticum astronomicum).
Finally some people take him for Cektrops. He lived in a time where wine was unknown. The pouring of the water is thought to be a symbol for the sacrifice of this element (instead of wine) for the gods (eubulus ap. eumd.l.c). The gods showed their gratetude giving him a place beneath the stars.