Aquila is a northern sky constellation that is found close to the celestial equator, and is therefore rich in galaxies, star clusters and nebulae. Meaning “the eagle” in Latin, the constellation was recorded by Greek astronomer Ptolemy around 150 AD, and is said to represent the bird which carried the thunderbolts of Zeus. Aquila’s brightest star, Altair, is a white subdwarf located just 16.8 light-years away that shines with a visual magnitude of 0.77, making it the night sky’s 12th brightest star.
Aquila is the 22nd biggest constellation, and can be observed from latitudes between +90° and -75°, although it is best seen in August. Altair in Aquila also forms one corner of a famous asterism known as the Summer Triangle, together with Deneb in Cygnus, and Vega in the Lyra. Aquila’s neighboring constellations include Aquarius, Capricornus, Delphinus, Hercules, Ophiuchus, Sagitta, Sagittarius, Scutum, and Serpens Cauda.
Aquila is included in the Hercules family of constellations, together with Hercules, Sagitta, Lyra, Cygnus, Vulpecula, Hydra, Sextans, Crater, Corvus, Ophiuchus, Serpens, Scutum, Centaurus, Lupus, Corona Australis, Ara, Triangulum Australe and Crux.
Aquila was born out of several different myths, with the Greek origin story associating it with the eagle that carried Zeus’ thunderbolts, and acted as his personal animal messenger. The eagle also carried the young Trojan prince Ganymede to Zeus to act as his cup-bearer, with the handsome youth represented by the nearby constellation of Aquarius.
Another myth states that Aquila is the eagle who protected the arrow of Eros, commemorated by the constellation Sagitta (arrow), while an alternate legend tells that it represents Aphrodite, who disguised herself as an eagle pretending to hunt Zeus disguised as a swan so that his love interest, Nemesis, would take pity on the swan and provide him with sanctuary. Zeus later commemorated the event by placing the swan and eagle amongst the stars as the constellations Cygnus and Aquila.
Stars in Aquila
– Altair (Alpha Aquilae) is a blue subdwarf located only 16.8 light years from the Sun, making it one of our closest stellar neighbors, as well as the night sky’s 12 brightest star with a visual magnitude of 0.77. It is 18 times more massive than our sun, and rotates rapidly, causing it to be flattened at its poles, instead of spherical in shape. It also moves rapidly across the sky, shifting by around a degree every 5,000 years. The star’s name is formed from the Arabic phrase ‘al-nasr al-ta’ir’, meaning “flying eagle”, while the ancient Sumerians and Babylonians knew Altair as the “eagle star.”
– Tarazed (Gamma Aquilae), the constellation’s second brightest star, is an orange giant (K3 II) situated around 461 light years from our solar system that shines with a visual magnitude of 2.72. It is around 100 million years old, and compared to the Sun is 95 times bigger, and 2,960 times brighter. The name Tarazed comes from the Persian phrase ‘šahin tarazu’, which translates as “the beam of the scale.”
– Deneb el Okab (Zeta Aquilae) is a blue-white star found 83.2 light years away with a visual magnitude of 2.99. It is in actual facts a triple star system whose main component is a white A-type dwarf that has two fainter 12th magnitude companion stars. Its name comes from an Arabic phrase meaning “the tail of the eagle.”
Other stars of interest in Aquila includes the yellow-white stars Alshain (Beta Aquilae) and Bezek (Eta Aquilae); the blue-white stars Al Thalimain (Iota Aquilae) and Tseen Foo (Theta Aquilae); and the pulsating variable star R Aquilae, which is a red-hued giant star found 690 light-years away whose apparent magnitude varies from 6 to 12 over a period of 9 months.
Notable Deep Sky Objects
– Hercules–Corona Borealis Great Wall (Great GRB Wall) is a massive concentration of billions of galaxies located 10 billion light-years away. The superstructure’s dimension’s are 10 billion light years by 7.2 billion light years by 1 billion light years, making it the most massive structure yet discovered in the known Universe.
– Phantom Streak Nebula (NGC 6741) is located around 7000 light years away, and has an apparent visual magnitude of 11. It is an example of a planetary nebula, which is rather a misnomer dating back to the 1780s, as when viewed through a telescope their round gas shells resembled the shapes of our solar systems’ gas giant planets. NGC 6741 was created after an aging star ejected its gaseous outer layers into space, which is now illuminated by radiation emitted by the star’s remnant located at the centre of the nebula.
– NGC 6709 is an open star cluster 9,100 light-years distant containing about 40 stars ranging from magnitudes 9 to 11. It can be seen clearly with even a small telescope, and sits 5 degrees to the southwest of Zeta Aquilae, where its stars form a sort of loose diamond shape.
– NGC 6755 is an open cluster of around a dozen stars, the brightest of which are of 12th and 13th magnitude. This cluster is found 4.5 degrees west of Delta Aquilae.
Other objects of interest in Aquila includes the planetary nebulaes NGC 6804, NGC 6781, and the Glowing Eye (NGC 6751).
The two meteor showers associated with the constellation of Aquila are called the June Aquilids and the Epsilon Aquilids, although both were detected using radar, and none have ever been photographed. The Epsilon Aquilids take place in mid-May, with its peak occurring on the 17/18th; while the June Aquilids occur from June 2 to July 2 every year, and at its peak can produce an hourly rate of up to 35 meteors.