Learn the stars, clusters, and nebula of the constellation Aquarius the Water Bearer.
Aquarius is a constellation best seen in the fall and is situated between the zodiac constellations of Pisces and Capricornus. The main shape consists of a boy or man holding a water jar from which water is pouring out.
Stars
The two brightest stars in Aquarius are the magnitude 2.9 Beta Aquarii and the magnitude 2.95 Alpha Aquarii, also known as Sadalmelik. The two stars are ten degrees apart, or about the width of your fist held at arm's length. The next brightest star is magnitude 3.27 Delta Aquarii, or Skat. A triple star (visual only, not physically related) is the stars of Psi Aquarii. Their magnitudes range from 4.2 to 4.9.
Clusters
The globular cluster M2 resides in Aquarius. M2 is above a line drawn between the Alpha and Beta stars. This globular cluster shines at magnitude 6.5 and lies about 37,000 light-years away. M72 is another globular cluster that can be found in Aquarius. If you draw a line from Alpha, through Beta, and extend it 11 to 12 degrees forward, you will run into M72. While M2 can be seen with binoculars, M72 is a magnitude 9.4 and is best located with a telescope. M72 lies 55,000 light-years away. An open cluster in the same area as M72 is M73, just over one degree east from the globular. It shines a bit brighter at magnitude 9 but is a smaller and less noticeable grouping of stars.
Nebulae
Close to M72 and M73 is the Saturn Nebula, or NGC 7009. This 8th-magnitude planetary nebula looks like the planet Saturn because its gassy halo includes a thin extension on both sides that look like rings. Another well-known nebula, the Helix Nebula (NGC 7293) lies in Aquarius. The Helix lies about 20 degrees below the stars Alpha and Beta. Although the Helix has a magnitude of 7.3, it is hard to observe because its light is extended over a large space. This nebula spreads out across 28 arcminutes, almost as large as a full moon. However its appearance in photographs is quite stunning.
Planets
Like all members of the Zodiac, Aquarius has planets (and the moon and sun) regularly passing through it. Currently Uranus is making its home here, in the eastern boundaries of the constellation. Uranus will reside in Aquarius until the year 2010, when it moves into Pisces. In 2010, Neptune moves into Aquarius from Capricornus.
The images of M2, M72, and the Helix are courtesy of Calvin College Observatory.
