Aquarius

by Shaphan Shank | Oct 1, 2022 | 0 comments

Helix Nebula, NGC 7293
Helix Nebula, NGC 7293. Photo © Dreamstime.com.

Aquarius is a sprawling constellation that stretches across nearly 40° of the southern sky on autumn evenings. This constellation lies south of the Great Square of Pegasus and north of the bright star Fomalhaut (the only bright star in the southern sky on autumn evenings at mid-northern latitudes).

To the ancients, Aquarius represented a man carrying water, but I can see little resemblance to a water carrier or anything else in the scattered stars of this constellation. However, though it lacks an eye-catching shape, Aquarius is home to several noteworthy deep sky objects.

One of these objects is M2, a globular star cluster that contains about 150,000 stars. M2 lies in the northern part of Aquarius, 5° north of the star Sadalsuud. You should be able to easily see the cluster with binoculars, although it will only look like a fuzzy star-like spot of light at such low magnification. Larger telescopes will show the cluster as a heavily concentrated ball of stars surrounded by a large halo that is fainter and less concentrated with stars. This cluster is also easy to observe with smaller scopes, but they will resolve fewer stars. With any size of telescope, you will need fairly high magnification to get the best views of the cluster.

Two noteworthy planetary nebulas, the Saturn Nebula and the Helix Nebula, lie within the boundaries of Aquarius. NGC 7009, the Saturn Nebula, is a small planetary that lies in the western part of Aquarius. To find this nebula, first find the star Epsilon Aquarii at the western end of Aquarius. From Epsilon Aqr, go roughly 6° southeast to the star Nu Aqr. NGC 7009 lies about 1° west of Nu Aqr.

Once you’ve found the nebula, use high magnification to see as much detail as possible. Through a telescope, NGC 7009 looks like a small bright blue or green oval. The nebula gets its popular name (Saturn Nebula) from two thin projections, reminiscent of Saturn’s rings seen edge-on, that extend from opposite ends of the nebula. You’ll need high magnification and at least an 8”–12” telescope to see these projections.

NGC 7293, the Helix Nebula, looks completely different from the Saturn Nebula. Although it too is a planetary nebula, the Helix appears much larger because it is the closest bright planetary to Earth. To find this nebula, first locate the star Skat, the brightest star in the southern part of Aquarius. From Skat, go about 7° southwest to the star Upsilon Aqr. The Helix is just 1° west of Upsilon.

This nebula has a pretty high overall brightness, but since its light is spread out over a large disk, its surface brightness is low. As a result, the Helix is easy to see with binoculars, but difficult to see with telescopes at high magnification. Binoculars show the Helix as a fuzzy ball of light that is nearly half the apparent diameter of the Moon.

You will get your best views with a telescope at low to moderate magnification. The nebula will probably appear no brighter with a telescope than it does with a binocular, but the extra magnification the telescope provides will reveal more detail. Much like the Ring Nebula, the Helix looks like a soft gray ring or doughnut, with fainter nebulosity in the central “hole.”

Star map Aquarius, Capricornus, Equuleus, Delphius, Aquila, Piscis Austrinus

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