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LAST month, we looked for the constellation of Cygnus, the swan. I like to think of our next target, the constellation of Aquila, the eagle, as a little sister to Cygnus: it is also named after a bird, has a similar cross shape and sits next to Cygnus in the sky. Aquila was the bird that carried thunderbolts for Zeus in Greek mythology and for Jupiter in Roman mythology.

We used the pattern of stars known as the summer triangle (pictured) to find Cygnus, and we can do the same for Aquila. The triangle is made up of three stars: Vega (at top of image), Deneb (left) and Altair (right). To spot them, look south after sunset in the northern hemisphere. Vega will be the highest of the three in the sky, with Deneb, which is in Cygnus, to its left and Altair below. In the southern hemisphere, look west. Altair will be highest, with Vega and Deneb nearest the horizon.

Altair is in Aquila and it represents the head of the eagle. Depending on where you live, the summer triangle will appear in different orientations, but Altair is recognisable because it sits furthest away from the other two stars that make up this feature.

Once you have identified the three stars of the triangle, draw an imaginary line from Vega to Altair. The rest of Aquila makes another line stretching out perpendicular to this line, in the direction away from Deneb, making the whole constellation look like a big cross.

Just like Cygnus, Aquila sits along the disc of the Milky Way, which means it is home to some great deep-sky objects – in other words, things that aren’t just single stars or part of our solar system. A planetary nebula called NGC 6790, a globular star cluster called NGC 6760 and an open cluster called NGC 6755 are great to look for near the centre of the constellation using a small telescope.

Near the tail of Aquila, in a constellation called Scutum, sits a V-shaped open star cluster called the Wild Duck, also known as M11. Named for its resemblance to a flock of flying ducks, this feature is about 6000 light years away and is estimated to be home to up to 11,000 stars.

In between Cygnus and Aquila, there are a few tiny constellations, each containing very faint stars. You may never have heard of these: Equuleus, the little horse; Delphinus, the dolphin; Sagitta, the arrow; and Vulpecula, the little fox. They can be difficult to spot, but a stargazing app will help.

In 1983, after a few drinks, a pair of Japanese astronomers decided to send a message towards Altair in the hope that there might be intelligent life on any planet orbiting it. The message contained the words for cheers in English and Japanese, plus the chemical symbol for methanol.

We don’t know of any planets around Altair, which is only about 17 light years away. Given the distance, if an alien civilisation had received the message, we could have had a reply in 2017.

Abigail Beall is a features editor at 91av and author of The Art of Urban Astronomy. Follow her @abbybeall

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