Astronomy, Guide to Space


12 Oct , 2008 by


Aquarius is a constellation of the zodiac and stretches from the celestial equator to the southern hemisphere. It is bordered by Pegasus, Equuleus and Delphinus at the north, Aquila to the west, Capricornus to the south-west, Piscis Austrinus and Sculptor to the south, Cetus to the east and Pisces to the north-east. Constellations of the zodiac are so named because of their position along the ecliptic plane – the path the Moon, Sun and planets follow across the visible sky. Aquarius is known as the “Water Carrier” and the stars Gamma, Eta, Zeta and Pi form a Y-shaped asterism known as the water jar.

In mythology, Aquarius was associate with the cup bearer of the gods – known to serve wine or water to Zeus. For his role, he was immortalized in the stars. Aquarius was also identified as the pourer of the waters which flooded the earth in the Great Flood, in the ancient Greek version of the myth. As such, the constellation Eridanus was sometimes identified as being a river poured out by Aquarius. It may also, together with the constellation Pegasus, be part of the origin of the myth of the Mares of Diomedes, which forms one of The Twelve Labours of Heracles. Its association with pouring out rivers, and the nearby constellation of Capricornus, may be the source of the myth of the Augean stable, which forms another of the labours. Aquarius is one of the oldest recognized constellations along the zodiac, the sun’s apparent path. It is found in a region often called the Sea due to its profusion of watery constellations such as Cetus, Pisces, Eridanus, etc. Sometimes, the river Eridanus is depicted spilling from Aquarius’ watering pot.

For binoculars and small telescopes, globular cluster M2 is a splendid object located in Aquarius. While it is not quite so well known, the four star asterism of M73 is also located in Aquarius and is an interesting sight in a small telescope. Small globular cluster, M72 also makes a very interesting small telescope target as well. For those with a who like binary stars, eta Aqr consists of a tight pair of F stars (F6IV and F3V) and both components are nearly of equal brightness showing 4.59 and 4.42 magnitude.

At a distance of just about 600 light ears the planetary nebula NGC 7293 – known as the Helix Nebula – is the closest of all planetaries and delivers an outstanding and interesting telescope view. Its apparent diameter is about the half of the Moon and is best viewed through binoculars or telescopes at minimal magnifications. It will appears to be a circular hazy patch, but to see it in its full beauty requires long-exposure photographs. However, NGC 7009 belongs to the brightest planetary nebulae and shows bright and easily detail to the telescope. Because of its shapely resemblance to the planet Saturn it is called Saturn Nebula! In larger scopes it appears as a bright inner ring surrounded by a patchy, blue colored disk. Small scopes show a misty greenish disk of 8th magnitude, but all show a delightful ansae which makes finding this planetary nebula worth the hunt.

There are five meteor showers associated with the constellation of Aquarius. The March Aquarids belong to the daylight showers which was first detected 1961 by C. S. Nilsson with radar methods. Activity can be detected from around March 11th to March 16 and may be associated with the Northern Iota Aquarid stream. The Southern Iota Aquarids begin around July 1st and end around September 18th. The peak date occurs on August 6th with an hourly rate of 7-8 meteors average. The Northern Iota Aquarids occur between August 11th to September 10th. The maximum peak occurs on or about August 25th with an estimated fall rate average of 5-10 meteors per hour. Both streams produce meteors with an average magnitude slightly fainter than 3. The Delta Aquarids are two distinctly different streams. The Southern Delta Aquarids begin about July 14th and end around August 18th with a maximum hourly rate of 15-20 peaking on July 29th. The Northern Delta Aquarids usually begin around July 16th and last through September 10th. The peak date occurs on or around August 13th with a maximum fall rate of about 10 meteors per hour. The Eta Aquarid meteor shower begins about April 21th and ends around May 12th. It reaches its maximum on or about May 5th with a peak fall rate of up to 20 per hour for observers in the northern hemisphere and perhaps 50 per hour for observers in the southern hemisphere.

Source: SEDS
Constellation Map Provided by Your Sky

Tammy was a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status. (Tammy passed away in early 2015... she will be missed)

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