Aquila the Eagle soars along the Milky Way

The best time to see the constellation Aquila the Eagle in the evening sky is from July to November as it soars along the Milky Way. And, because our galaxy provides a starry backdrop, many clusters and nebulae lie within its borders. Aquila’s brightest star, Altair, is the southernmost corner star in the Summer Triangle. In mythology, Aquila carried Zeus’ thunderbolts for him.

Catch the wonder of the night sky. Subscribe to EarthSky’s free daily newsletter for the latest in science, stars, planets and more.

The stars of Aquila the Eagle

The brightest star in Aquila is Alpha Aquilae, or Altair. At magnitude 0.76, it is one of the three bright stars that mark the corners of the Summer Triangle. Deneb and Vega are the other two, and they lie higher in the sky, closer to the zenith on summer evenings. Altair lies just 17 light-years away from Earth.

Additionally, two moderately bright stars lie on either side of Altair. To the southeast is Beta Aquilae, or Alshain. This magnitude 3.71 star lies 45 light-years away. To the other side of Altair is Gamma Aquilae, or Tarazed. At magnitude 2.72, it’s brighter than Alshain but lies much farther away at 461 light-years. This trio of stars is found near the head of Aquila the Eagle.

Then, the star marking Aquila’s back is Delta Aquilae, at magnitude 3.36 and 50 light-years away. Likewise, Theta Aquilae marks the left wing. It shines at magnitude 3.26 from a distance of 286 light-years. The right wing, which points to Vega, holds Zeta Aquilae at magnitude 2.99 and 83 light-years distant. Lastly, the star at the end of the tail of the Eagle is Lambda Aquilae at magnitude 3.43, lying 125 light-years away.

Globular clusters

While there are no Messier objects in Aquila, there is still a lot to see, especially if you have a big enough telescope. For example, two globular clusters lie in Aquila: NGC 6749 and NGC 6760.

The two globular clusters are in the vicinity of Delta Aquilae. NGC 6760 shines at magnitude 9.1. Then, about 2 degrees farther away is NGC 6749 at magnitude 12.

In addition, several open clusters lie in Aquila, but most of them are faint. With this in mind, the best one to observe is NGC 6755, a 7.5-magnitude grouping found near the star marking the back of the Eagle. Another good open cluster to try for is NGC 6709, which, at magnitude 6.7, appears in binoculars. NGC 6709 is fairly near Zeta Aquilae, the upper wing of the Eagle. Between these two clusters is yet another cluster, NGC 6738. This sparse cluster is 8th magnitude.

Also, a lot of observers who come to Aquila use it to starhop to a cluster just over the border of the constellation Scutum the Shield. The Wild Duck Cluster, M11, shines at magnitude 6.3, making it brighter than any of the clusters in Aquila. Here’s how to find it.

Nebulae of Aquila

A number of nebulae lie along the line that marks the body of the Eagle, but only one is bright enough to reach even 10th magnitude. NGC 6790 lies a little less than 2 degrees from the star that marks the back of the Eagle in the direction of its tail.

Good luck tracking down these tough-to-spot, faint objects in Aquila the Eagle. Or, you can always just scan the area in binoculars and see what materializes.

Aquila from the Southern Hemisphere

Via Daniel Gaussen, Founder & Guide – Stargaze Mackenzie – New Zealand

For Southern Hemisphere observers, Aquila the Eagle takes on a different appearance as it culminates (gets the highest) in the northern sky. The constellation appears upside down compared with its orientation in the Northern Hemisphere, with Altair, marking the Eagle’s head, at the lower part of the constellation and its body and wings extending upward into the sky.

The constellation is still best placed for viewing from about July through November, but this falls during the winter and early spring months in the Southern Hemisphere, when still, cold nights are punctuated by the brilliant central regions of the Milky Way high overhead.

From Twizel, New Zealand (44 degrees south latitude), Altair rises to about 37 degrees above the northern horizon. From Auckland, see it climb to around 52 degrees and in Sydney to about 55 degrees Though reasonable in altitude, its companion stars of the Summer Triangle sit considerably lower on the horizon.

Look for the bright star Altair on one side of the Milky Way and Vega on the other. The two stars can appear like they are separated by a broad, shimmering river of stars. This celestial scene has inspired the Japanese festival of Tanabata, based on the legend of two lovers, represented by Altair and Vega, who are separated by the Milky Way and allowed to meet only once a year.

Although Aquila contains several star clusters and nebulae, many are challenging targets for Southern Hemisphere observers because of their faintness and relatively low altitude above the northern horizon. With the right conditions, however, they can be rewarding targets, particularly for astrophotographers where long-exposure imaging can reveal interesting detail even when they are difficult to see visually.

Bottom line: Aquila the Eagle is home to the bright star Altair, which forms one corner of the Summer Triangle. And you can see this constellation at its best in northern late summer or early fall evenings.