Corvus is the 70th largest of the 88 constellations, and consists of 4 main stars which form a quadrangle in the night sky, the brightest of which is a blue-white giant star of 2.59 magnitude called Gienah. The name Corvus means “crow” or “raven” in Latin, and it is associated with the nearby constellation of Crater (Cup), and Hydra (Water Snake).
This tiny constellation takes up an area of only 184 square degrees of the southern sky, and can be seen by people located between latitudes +60° and -90°. Corvus can be seen by northern hemisphere observers during the winter and spring time from January until May, although it is best seen at around 9 PM (Local Time) during the month of May. Look for the Crow perched on the back of Hydra, between Virgo to the northwest, and Crater, almost due east. Four of the brightest stars in the constellation form a distinctive quadrilateral figure in the sky, which is not difficult to find.
The constellation is taken to represent the god Apollo’s once-sacred crow. While most mythological figures were placed in the sky as a sign of honour and respect, Corvus was placed in the sky as punishment for failing to fetch water for Apollo in a timely fashion. Instead, the crow dallied by a fig tree several days eating its fruit, and subsequently lied to Apollo by blaming the serpent Hydra for blocking the spring. Unconvinced by his lies, Apollo then flung Corvus, the cup, and the water snake he brought in his claws into the heavens, while Corvus was also punished with eternal thirst, which it why crows have a rasping caw, unlike other birds which sing.
Although Corvus has no bright stars, its four brightest stars form a distinctive asterism known as THE SAIL (SPICA’S SPANKER), which is made up of Delta, Gamma, Epsilon, and Beta Corvi. The two stars Gamma and Delta Corvi serve as pointers to the star Spica, the most luminous star in Virgo, and the 15th most luminous star in the entire sky.
– Gienah (Gamma Corvi) is a B8 III-class giant blue star with an apparent visual magnitude of 2.59, making it the most luminous star in the constellation. Located 154 light years from Earth, its only other distinguishing feature is that it is a suspected binary star.
– Kraz (Beta Corvi) is a G-type yellow giant star located about 140 light years away, and the second most luminous star in the constellation, with an apparent visual magnitude that varies between 2.60, and 2.66. Although the star was named “Kraz” comparatively recently, nobody is quite sure who named it thus, or why. What is certain though, is that Kraz is at least 160 brighter than the Sun.
– Eta Corvi, an F2 V-class main sequence dwarf with an apparent visual magnitude of 4.31, is the sixth most luminous star in the constellation, but what sets it apart from other stars in Corvus is that like the star Vega in Lyra, it is surrounded by a debris disc. However, recent research has revealed the presence of a second debris disc, which is unusual for a star of this size.
Even though the constellation has no Messier objects, it is home to the Antennae Galaxies, one of the most spectacular and famous galactic mergers known, as well as one of the most beautiful planetary nebulae.
– Antennae Galaxies (NGC 4038/NGC 4039, Caldwell 60/61); Also sometimes known as the Ring Tail, this merger is a member of the NGC 4083 Group, an assembly of galaxies with between 13 and 27 members that fall in both Corvus and the neighbouring constellation Crater. The pair of colliding galaxies has a combined apparent visual magnitude of 11.2 from a distance of about 45 million light years away. The encounter is estimated to have started about 900 million years ago. Around 600 million years ago, the galaxies actually collided and passed through each other, which caused both galaxies to begin ejecting stars about 300 million years ago.
During the past 300 million years the number of ejected stars had grown so large that collectively, they appear as an extension of the pairing that resembles the antennae of an insect, hence the name, Antennae Galaxies. One such antenna can be seen as the blue, fuzzy area to the right of the curved, pink star forming region in the upper galaxy. It is estimated that the merger will be complete in about 400 million years’ time, when the pair will settle down into a large elliptical galaxy.
– NGC 4361 is arguably one of the most spectacular planetary nebulae known and among the largest. This particular example spans an area of about 1.3 degrees, and unlike most planetary nebulae that have two lobes of ejected matter, this one has four distinct lobes, giving the nebula the appearance of a small irregular galaxy. Note the 13th magnitude remains of the progenitor star in the centre of the bubble of gas and dust.
The only meteor shower associated with the Crow is the Corvids, which seems to have disappeared after its discovery in 1937 in what is now Namibia. In that year, the shower peaked on June 26th, with a maximum rate of 13 meteors per hour. This shower has never been observed after 1937, and no trace of it has since been detected even with radio and radar surveys.
Ptolemy clearly drew heavily on the Babylonian crow constellation MUL.UGA.MUSHEN, which was depicted in Babylonian charts as a bird perching on the tail of a serpent of some sort. In Babylonian times, the constellation was linked to Adad, the deity of Rain and Storms, no doubt because in those times, the constellation rose just before the onset of the wet season.
As of 2016, the constellation has two stars with one planet each. Neither star is visible to the naked eye.