Aquarius is part of the zodiac and is located in the southern hemisphere. It is found in a part of the sky nicknamed the Sea. This region is so named because of its abundance of water-related constellations including Pisces, Capricornus, Eridanus, and Cetus.
Aquarius was cataloged by the 2nd Century Greek astronomer Ptolemy. The constellation is recognized for its collection of notable celestial objects including Messier objects, galaxies and even nebulae. Its name is Latin for “the water bearer”, and it is represented by a human healer pouring water onto the ground.
How to Locate Aquarius
Aquarius’s form may be abstract and difficult to immediately spot, but it is actually the 10th biggest constellation in the sky. It is also surrounded by a number of significant constellations including Aquila, Capricornus, Pegasus, Pisces, Piscis and Sculptor among others. If you are not using a star map, and don’t know your pointers well, the simplest way to spot Aquarius would be to locate it by its bordering constellations.
Because the stars in Aquarius are not significantly bright, you will need as little light pollution as possible to observe it well. Regardless of the hemisphere you’re in, October and November is when it will be highest in the sky for easy locating.
This constellation as an asterism within it known as the Water Jar; a defined zig-zag of stars best viewed under dark skies. It points to Sculptor on one end and ends between Capricornus and Pisces on the other.
Aquarius Mythology and History
There are a few myths surrounding the constellation Aquarius. The most prominent one is from Greek mythology which follows Ganymede, a young and handsome man. Because of his appeal, Zeus chose Ganymede as his own and made him a cup-bearer to the gods.
Ganymede eventually grew tired of serving Zeus and in an act of rebellion, spilled all the nectar, water and wine that was meant for them. According to the myth, this caused an onslaught of rains that fell to Earth and subsequently flooded it.
Zeus’s first instinct was to punish Ganymede, but because he had a soft spot for him, he was immortalized as the constellation Aquarius instead.
In other myths, Aquarius is associated with Deucalion, Prometheus’ son and a survivor of the great, devastating flood. In Babylonian stories, Aquarius is sometimes linked to Enki, whose mythology features water quite a bit. Egyptian folklore links Aquarius to god of the river Nile.
Stars in the Constellation Aquarius
There are only two stars brighter than magnitude 3.0 in Aquarius, but what is notable is that this constellation has a number of stars with known exoplanets.
- Beta Aquarii/Sadalsuud: This is the brightest star in the constellation, shining at magnitude 2.87. It is over 538 light-years away from Earth and is a rare yellow supergiant star. Beta Aquarii is actually a triple (and suspected multiple) star system. Its brightest feature is Beta Aquarii A, which has two optical companions. This star’s traditional name Sadalsuud comes from an Arabic phrase loosely meaning “luckiest of all.” To a few cultures, Beta Aquarii represents the dawn of spring. This star is 6 times more massive than the Sun and is over 2,000 times more luminous than the Sun.
- Alpha Aquarii/ Sadalmelik: This 2.95 magnitude star is another yellow supergiant in the constellation. It lies approximately 520 light-years away and is a few thousand times the luminosity of our Sun.
- Delta Aquarii/ Skat: The third brightest star in Aquarius, Delta Aquarii is a magnitude 3.28 star that is over 159 light-years away from the Sun. It has been suggested that this star be included in the Ursa Major Moving Group of stars because of similarities in velocity and origin. The Delta Aquariids meteor shower is often tied to the star.
- Gamma Aquarii/ Sadachbia: This is a spectroscopic binary star. This type of binary star is discovered and studied by examining the emission and absorption lines of the stars’ spectrum. Gamma Aquarii has a period a little shy of 2 months, and a magnitude of 3.86. It is found about 163 light-years away. Its traditional name in Arabic keeps with the theme of other stars in the constellation and can be translated as “luck of homes”.
- R Aquarii: R Aquarii stands out because it is a symbiotic star. This is a type of binary system in which a red giant loses its stellar material through stellar winds (or other processes) which then form an accretion disk around a hot, white dwarf companion. The dwarf companion in R Aquarii in turn then sometimes ejects excess materials to form a strange and intricate nebula called Cederblad 211. R Aquarii is a magnitude 7.69 star that is approximately 652 light-years away.
- Psi-1 Aquarii/ 91 Aquarii: Psi-1 Aquarii is part of a triple star system. Psi-1 Aquarii is the primary star; a magnitude 4.22 orange giant with a known exoplanet orbiting it. It was discovered in 2003. Psi-1 Aquarii is approximately 150 light-years away.
- Gliese 849: This is a red dwarf star. It lies 29 light-years from Earth and is another star in Aquarius with a known planet in its orbit. The planet, Gliese 849 b, was discovered in 2006.
- Gliese 876: This star is also a red dwarf, found about 15.2 light-years away. Gliese 876 has four exoplanets orbiting it. This was confirmed in 2010. Its closest planet is said to likely be either a small gas planet similar to Neptune or a bigger terrestrial planet. Even though Gliese 876 is fairly close to us, it has a magnitude of 10.1, and cannot be seen with the naked eye.
- Epsilon Aquarii: This star is a white subgiant and a suspected a variable star. Its magnitude is 3.8 and it is found about 208 light-years away. Epsilon Aquarii is also known by its Arabic names, Albali and Nir Saad Bula.
Deep Sky Objects in Aquarius
Aquarius has a range of deep sky objects for you to enjoy. This includes three Messier objects, galaxies, and nebula. Aquarius is a great spot to aim your binoculars or telescopes, and is home to a few popular objects among amateur astronomers.
- Messier 2/ NGC 7089: This magnificent globular cluster lies close to Aquarius’s brightest star, Beta Aquarii. It is an estimated 13 billion years old and lies 33,000 to 37,000 light-years away. M2 measures about 175 light-years across and contains 150,000 or more stars. This making it one of the biggest globular clusters to date. M2 includes 21 known variable stars. Its brightest stars are red giants and yellow giant stars with magnitudes over 13.0. The globular cluster’s magnitude is 6.3, so you can spot it under a really dark sky.
- Messier 72/ NGC 6981: Another globular cluster, M72 has an apparent magnitude of 9.3 and is found about 54,500 light-years away. It spans well over 100 light-years in diameter and includes a number of blue giants, implying that it is still quite a young cluster. It is also noted for its abundance of variable stars. Messier 72’s brightest star is magnitude 14.2. The cluster is even difficult to view through binoculars due to its overall faintness. It is best to use a larger telescope, but even then it may appear faint and fuzzy.
- Messier 73/ M73/ NGC 6994: Messier 73 is a nice asterism to view with the unaided eye and through binoculars. It is made up of 4 stars that seem close to one other but are not connected at all. M73 was thought to be a very sparsely spaced open cluster until 2002. Evidence showed that the stars in it varied too greatly in their distance to Earth, and do not move in the same directions. M73 is at least 2,511 light-years away.
- Saturn Nebula/ NGC 7009/Caldwell 55: The Saturn Nebula is a planetary nebula. Its central star is a white dwarf with a luminosity 20 times that of the Sun and a magnitude of 11.5. UV radiation emitted from this star is believed to be the cause of the Saturn Nebula’s distinct green tint. The nebula was discovered by Sir William Herschel in the 18th century, though William Parsons, an English astronomer and telescope maker, was the one who gave it its name in the 19th century. The nebula has a similar shape to Saturn when viewed through a large telescope, hence its name.
- Helix Nebula/ NGC 7293/ Caldwell 63: The Helix Nebula is also a planetary nebula about 695 light-years away. It is one of the brightest and closest nebulae to the Solar System. The nebula spans only 2.5 light-years, but is so distinct it has earned the name the “Eye of God”. Set up your telescope with an appropriate filter to get the best out of viewing this nebula.
- Atoms for Peace Galaxy/ NGC 7252: Atoms for Peace Galaxy is a strange elliptical galaxy believed to be the product of two disk galaxies that collided. It earned its somewhat unconventional name due to its shape: it is reminiscent of the depictions of an atom and electron (and taken from Dwight Eisenhower’s speech of the same name). The galaxy has an apparent magnitude of 12.7 and lies approximately 20 million light-years away. Its central region contains a few hundred extremely luminous clusters that house hot, young stars. You can also find a pinwheel-like disk deep inside the Atoms for Peace. It rotates in the opposite direction of the galaxy itself.
- NGC 7727: This spiral galaxy is located 76 million light-years away and has an apparent magnitude of 11.5. Astronomers suspect the galaxy formed when two other spiral galaxies collided a billion years ago. Models show that NGC 7727 may evolve to an elliptical galaxy in time.
- Planetary systems in Aquarius: Because of the abundance of exoplanets found in Aquarius, it is significant in the search for extra-terrestrial life. Beyond the planets known to orbit Gliese 876 and Gliese 849, it is worth mentioning that the red dwarf star TRAPPIST-1 has seven Earth-like planets, three of which may contain water. As of 2013, twelve exoplanets have been listed in the constellation.
Aquarius Meteor showers
There are three prominent meteor showers in Aquarius.
The Eta Aquariids are the strongest shower, sometimes reaching up to 40 meteors per hour. It begins late April and ends mid-May, peaking between May 5th and 6th, with an average 35 meteors per hour.
The Delta Aquariids meteor shower has two radiant points. The first is Aquarius’s southern region, while the other is the northern circlet of the Pisces asterism. It usually peaks from the end of July through to the beginning of the second week and sometimes even the third week in August. They have about 20 and 10 meteors hourly respectively.
The Iota Aquariids is somewhat weaker, with less than 10 meteors per hour, peaking at the end of the first week in August.