Aquarius
Origin
Aquarius is one of the constellations of the zodiac, lying on the Sun’s apparent path across the sky. Aquarius is the ‘water carrier’ and is located in a part of the sky sometimes called the Sea because there are other water-based constellations nearby. Aquarius is a very old constellation and was listed by Ptolemy in the second century.
Bright Stars
Aquarius is not a bright constellation. Its brightest star is Sadalsuud (beta Aquarii) shining at a magnitude of 2.91. Sadalmelik (alpha Aquarii) is very close in brightness at magnitude 2.94.
Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani
Notable Objects
Messier 2 is a rich globular cluster and an easy catch in small telescopes and binoculars at a magnitude of 6.5. Messier 2 is 37,000 light-years from Earth. Messier 72 is a 9th-magnitude globular cluster located 56,000 light-years away from Earth. Messier 73 is a small cluster of four stars that appear to be a chance alignment rather than a sparse open cluster.
NGC 7009 is a planetary nebula commonly called the Saturn Nebula owing to its distinctive shape. This 8th-magnitude nebula has a central star with a magnitude of 11.3. NGC 7293 is the famous Helix Nebula. The Helix Nebula has a magnitude of 6.0 but a very low surface brightness owing to its large size (0.25 square degrees). The Helix Nebula is the closest planetary nebula to Earth at 650 light-years.
There are three meteor showers associated with Aquarius. The Eta Aquariids are the strongest meteor shower radiating from Aquarius and peak between 5 and 6 May with a rate of approximately 35 meteors per hour.
The Delta Aquariids is a double radiant meteor shower that peaks first on 29 July and second on 6 August. The first radiant is located in the south of the constellation, while the second radiant is located in the northern circlet of the Pisces asterism. The southern radiant's peak rate is about 20 meteors per hour, while the northern radiant's peak rate is about 10 meteors per hour.
The Iota Aquariids is a fairly weak meteor shower that peaks on 6 August, with a rate of approximately eight meteors per hour.