the fly · pronounced MUSS-kuh. Musca is a compact, bright-edged southern constellation immediately below Crux. Dutch navigators recorded its stars in the 1590s, and early atlases alternated between a bee and a fly before Musca became standard. Alpha and Beta Muscae make it easy to locate from the Southern Cross. The Milky Way field contains globular clusters NGC 4833 and NGC 4372, the long Dark Doodad dust lane and the extraordinary bipolar planetary nebula MyCn 18.
About Musca
Musca is one of the 88 constellations recognized by the International Astronomical Union. Its standard three-letter abbreviation is Mus, and astronomers use the genitive form Muscae when naming stars associated with it. The constellation's reference position lies around right ascension -11.0 hours and declination -73 degrees.
Its location places it in the southern sky. For a typical mid-latitude observer, this part of the celestial sphere is especially well placed during spring evenings. Exact visibility depends on latitude, local horizon, date and time.
History and mythology of Musca
Bee, fly and the southern voyages
Pieter Dirkszoon Keyser and Frederick de Houtman recorded the stars, Petrus Plancius mapped them as a bee, and Johann Bayer published the figure in 1603. Later names included Apis and Musca Australis before Musca prevailed.
Why “southern” disappeared
The qualifier Australis distinguished it from a proposed northern fly near Aries. When that northern figure became obsolete, the IAU retained the shorter name Musca.
A dark lane beside the Cross
Musca lies on the southern Milky Way. Molecular clouds create the Dark Doodad and nearby Coalsack complex, while foreground stars and remote clusters layer very different distances into one small visual field.
The modern astronomical region
The IAU adopted the three-letter abbreviation and standard constellation name in 1922. Eugène Delporte then published the coordinate boundaries in 1930, turning the inherited figure into an exact address for cataloguing every object inside it.
How to find Musca
- Find the Southern Cross, then look immediately southeast of Acrux. Alpha and Beta Muscae form a conspicuous pair below the Cross.
- Trace Gamma, Delta and Epsilon Muscae to complete the compact fly pattern. From dark sites the Milky Way background makes the region easy to recognise.
- March through June evenings are convenient in the Southern Hemisphere. Musca is circumpolar from many southern locations and invisible from most of Europe and North America.
- Sweep north of the main pattern for NGC 4833. The Dark Doodad is best in binoculars or wide-field photographs as a narrow absence of stars.
Bright stars in Musca
Alpha Muscae
Notable star- Magnitude
- 2.69
- Distance
- about 315 light-years
A hot blue-white subgiant and Beta Cephei pulsator, the constellation’s brightest star.
Beta Muscae
Notable star- Magnitude
- 3.04
- Distance
- about 340 light-years
A close binary of two blue-white stars, forming the prominent naked-eye pair with Alpha.
Delta Muscae
Notable star- Magnitude
- 3.62
- Distance
- about 91 light-years
An orange giant whose warm colour contrasts with Musca’s brighter blue B stars.
Gamma Muscae
Notable star- Magnitude
- 3.84
- Distance
- about 325 light-years
A blue-white main-sequence star and slowly pulsating B variable in the northern part of the pattern.
Deep-sky objects in Musca
NGC 4833
A bright southern globular near the Coalsack, visible in binoculars as a fuzzy spot and partially resolved by modest telescopes.
NGC 4372
A large, low-surface-brightness globular partly obscured by foreground dust. Dark, transparent skies are critical despite its substantial total brightness.
Dark Doodad Nebula
A long, narrow dust lane catalogued as part of the Musca molecular cloud, striking in wide-field photographs against dense Milky Way stars.
MyCn 18 (Engraved Hourglass Nebula)
A young bipolar planetary nebula whose Hubble image shows nested hourglass lobes and an off-centre central star.
Interesting facts about Musca
- Musca's name means the fly. Pieter Dirkszoon Keyser and Frederick de Houtman recorded the stars, Petrus Plancius mapped them as a bee, and Johann Bayer published the figure in 1603.
- Alpha Muscae is listed at magnitude 2.69. A hot blue-white subgiant and Beta Cephei pulsator, the constellation’s brightest star.
- NGC 4833 is a globular cluster. A bright southern globular near the Coalsack, visible in binoculars as a fuzzy spot and partially resolved by modest telescopes.
- The qualifier Australis distinguished it from a proposed northern fly near Aries.