Constellations of the Month: May – Musca:
We continue May with the last constellation of the month, Musca, “The Fly.”

Musca constellation map courtesy of Openverse

Musca, “The Fly” – Musca is a constellation located in the southern hemisphere, and symbolizes “the fly” in Dutch. Musca is found south of the Southern Cross (Crux). It was created by Dutch astronomer Petrus Plancius using observations by Pieter Dirkszoon Keyser and Frederick de Houtman in the late 1500s. It was first shown in Johann Bayer’s 1603 celestial atlas, Uranometria. Notable features include Nova Muscae 1991, a binary system with a black hole, and various nebulae and globular clusters.

Engraved Hourglass Nebula (MyCn 18) courtesy of Openverse

Key points regarding Musca:

• Meaning: The term “Musca” translates to “The Fly” in Latin. Musca is part of the Johann Bayer family of constellations, which includes Apus, Chamaeleon, Dorado, Grus, Hydrus, Indus, Pavo, Phoenix, Tucana, and Volans. Within Musca, there is one star that has known planets, and it does not feature any Messier objects. The most luminous star in this constellation is Alpha Muscae, which has an apparent magnitude of 2.69. Additionally, there are no meteor showers linked to this constellation. Musca lacks any formally designated stars.
• Notable stars: Alpha Muscae is a blue-white star that is between the dwarf and subgiant stages of evolution, classified as B2 IV-V. It has an apparent magnitude of 2.69 and is about 315 light years away. This star is the brightest in the Musca constellation, with a mass 8.8 times that of the Sun and a luminosity 4,000 times greater. It rotates quickly and shows brightness variations due to pulsations. Beta Muscae is a binary star system with two blue-white main sequence dwarfs, separated by 1.206 arc seconds. Its combined apparent magnitude is 3.05 and it is about 340 light years away. Beta Muscae A and B have masses of 7.35 and 6.40 solar masses, respectively, and they have an orbital period of 194 years. Delta Muscae, the closest star to Earth in the Musca constellation, is a spectroscopic binary system at 91 light years away. Lambda Muscae is a white giant, marking the fly’s tail in the constellation, located 128 light years away. Gamma Muscae is a blue-white dwarf about 325 light years away. Epsilon, Mu, and various HD stars are other stars in the region, each with specific characteristics and distances. Nova Muscae 1991 is a binary system containing a black hole candidate that can produce X-ray outbursts. The black hole is seven times more massive than the Sun, while its companion star has three-quarters of the Sun’s mass.
• Other features: NGC 5189 is a planetary nebula in Musca, discovered by James Dunlop in July 1826. It has an apparent magnitude of 8.2 and is about 3,000 light years away. It appears S-shaped in telescopes, similar to a barred spiral galaxy, which is why it’s also called the Spiral Planetary Nebula. NGC 4372 is a globular cluster in Musca with an apparent magnitude of 7.8, located around 18,900 light years from Earth. The Engraved Hourglass Nebula, discovered in the early 20th century by Annie Jump Cannon and Margaret W. Mayall, has an apparent magnitude of 13 and is about 8,000 light years away. NGC 4833 is another globular cluster in Musca, with an apparent magnitude of 7.79 and is approximately 21,200 light years distant. Discovered by Nicolas Louis de Lacaille, it is partially covered by dust and has a radius of 42 light years. The Dark Doodad Nebula is a dark nebula near NGC 4372 and the Coalsack Nebula in Crux. It is part of the Musca molecular cloud, spans about 3 degrees in the sky, and was named by Dennis di Cicco in 1986. It is over 30 light years wide and lies around 700 light years from Earth.
• Mythology: Musca is one of the 12 constellations introduced by Dutch navigators Keyser and de Houtman during their expeditions in the late 16^th century. In de Houtman’s 1603 catalogue, it was called De Vlieghe, meaning “the fly” in Dutch. The cartographer Petrus Plancius first showed the constellation on his 1598 globe without a name. Johann Bayer, in his star atlas Uranometria, named it Apis, the Bee, which was used for about 200 years. The name Musca first appeared in 1602 on a globe by Willem Janszoon Blaeu. Plancius named it Muia in 1612. It was also known as Musca Australis, the Southern Fly, before being shortened to Musca by Nicolas Louis de Lacaille.
• Visibility: Musca is the 77^th largest constellation, covering an area of 138 square degrees. It is situated in the third quadrant of the southern hemisphere (SQ3) and is visible at latitudes ranging from +10° to -90°. The constellations that border Musca include Apus, Carina, Centaurus, Chamaeleon, Circinus, and Crux. The name Musca is pronounced /ˈmʌskə/. In English, this constellation is referred to as the Fly. The genitive form of Musca, which is utilized in the naming of stars, is Muscae (pronunciation: /ˈmʌsiː/). The three-letter abbreviation, which was established by the International Astronomical Union (IAU) in 1922, is Mus.

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Constellations:

Blackboard with the Musca constellation drawn in the middle. by Pexels

Constellations of the Month:
May – Musca

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