Orion's Sword is a compact asterism in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Orion Orion may refer to: Common meanings * Orion (constellation), named after the mythical hunter * Orion (mythology), a hunter in Greek mythology Arts and media Fictional entities Characters and species * Orion (character), a DC Comics c ...

. It comprises three stars ( 42 Orionis, Theta Orionis, and

Iota Orionis Iota Orionis (ι Orionis, abbreviated ι Ori) is a Star system, multiple star system in the celestial equator, equatorial constellation of Orion (constellation), Orion the hunter. It is the eighth-brightest member of Orion with an Appa ...

) and M42, the

Orion Nebula The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula in the Milky Way situated south of Orion's Belt in the Orion (constellation), constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It ...

, which together are thought to resemble a

sword A sword is an edged and bladed weapons, edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than a knife or dagger, is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter ...

or its

scabbard A scabbard is a sheath for holding a sword, dagger, knife, or similar edged weapons. Rifles and other long guns may also be stored in scabbards by horse riders for transportation. Military cavalry and cowboys had scabbards for their saddle ring ...

. This group is south of the prominent asterism,

Orion's Belt Orion's Belt is an asterism in the constellation of Orion. Other names include the Belt of Orion, the Three Kings, and the Three Sisters. The belt consists of three bright and easily identifiable collinear star systems – Alnitak, Alnilam, ...

. Fables and old beliefs are in Europe dominated or widely influenced by those of the Greco-Roman narratives. Beyond Europe this grouping is quite widely referenced as a weapon just as the majority of cultures perceived Orion's standout asymmetrical "hourglass" of seven very bright stars as a human.

Components

Orion Nebula

The Orion Nebula consists of one of the nearest (thus in the

Milky Way Galaxy The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are ...

), massive

molecular cloud A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...

s (30 - 40 light years in diameter) about 1,300 light years from the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

. This makes the nebula potentially the closest

HII region An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...

to Earth, a mass of hydrogen that has been ionized by nearby, hot, young stars. Regions like this are called stellar nurseries, nurturing the birth of multiple young stars such as the Orion Nebula Star Cluster. These are a hallmark of the asterism.

Main stars

'' 42 Orionis,'' also called c Ori, is a B1V magnitude star in the northern half of the Orion nebula. '' Theta Orionis'' has a more central position in the nebula, and is actually composed of a multi-star system. ''

'' is one of the brightest in the collection, in the south of the Orion nebula. ''Iota Orionis'' is a spectroscopic binary system, with a variable magnitude of O9III.

Scientific studies

Given the scientific significance of M42, Orion's Sword is a popular spot for stellar and protostellar studies. Using the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

, O'dell et al. focused on identifying previously unseen features of the nebula, such as high-ionization shocks, compact sources, and

protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk; while the two are sim ...

s. Some studies have focused on the sword region overall. Gomez & Leda found that less than half of the OB and Hα stars in this region are associated with well-defined stellar clusters. This positional similarity, as well as the high star formation rates and gas pressure in the nearby molecular cloud, confirms the previous notion that old, foreground OB stars triggered

star formation Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—Jeans instability, collapse and form stars. As a branch of astronomy, sta ...

in this cloud.

References in history and culture

Hyginus Hyginus may refer to: People *Hyginus, the author of the '' Fabulae'', an important ancient Latin source for Greek mythology. *Hyginus, the author of the ''Astronomia'', a popular ancient Latin guide on astronomy, probably the same as the author ...

described three faint stars where the sword is depicted in the constellation Orion, in his book ''De Astronomia''.

Aratus Aratus (; ; c. 315/310 240 BC) was a Greek didactic poet. His major extant work is his hexameter poem ''Phenomena'' (, ''Phainómena'', "Appearances"; ), the first half of which is a verse setting of a lost work of the same name by Eudoxus of Cn ...

goes into significant detail about the Orion constellation as well, proclaiming: ''"Should anyone fail to catch sight of him (Orion) up in the heavens on a clear night, he should not expect to behold anything more splendid when he gazes up at the sky."''

Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, orator, writer and Academic skeptic, who tried to uphold optimate principles during the political crises tha ...

and

Germanicus Germanicus Julius Caesar (24 May 15 BC – 10 October AD 19) was a Roman people, Roman general and politician most famously known for his campaigns against Arminius in Germania. The son of Nero Claudius Drusus and Antonia the Younger, Germanicu ...

, the translators of Aratus's ''Phaenomena'', expressed it as ,

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "sword". Arabic astronomers also saw this asterism as a sword ( ), calling it ("sword of the powerful one" or "sword of the giant"). Orion is one of the few constellations to have parallel identities in European and Chinese culture, given the name ''Shen'', the hunter and warrior. Chinese astronomers made the sword a sub-constellation within ''Shen'' called ''Fa''. In the myths of the Nama of Namibia and the western Cape, this was the arrow of the husband of the

Pleiades The Pleiades (), also known as Seven Sisters and Messier 45 (M45), is an Asterism (astronomy), asterism of an open cluster, open star cluster containing young Stellar classification#Class B, B-type stars in the northwest of the constellation Tau ...

, daughters of the sky god, who was represented by Orion's SW main star

Rigel Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...

. When he fired his arrow at three zebras (Orion's belt) and missed; he was too afraid to retrieve the arrow due to its proximity to a fierce lion, represented by

Betelgeuse Betelgeuse is a red supergiant star in the constellation of Orion (constellation), Orion. It is usually the List of brightest stars, tenth-brightest star in the night sky and, after Rigel, the second brightest in its constellation. It i ...

. Therefore, he sits in the cold, suffering from hunger but too ashamed to return home. Regionally the prevailing cold breezes and currents come from that direction. The

Tswana Tswana may refer to: * Tswana people, the Bantu languages, Bantu speaking people in Botswana, South Africa, Namibia, Zimbabwe, Zambia, and other Southern Africa regions * Tswana language, the language spoken by the (Ba)Tswana people * Tswanaland, ...

to the east traditionally call the unusually bright nebula and its companions , three dogs which chase the three pigs (the belt). This serves as an etiological myth for why pigs have their litters in the same season Orion is prominent in the sky. Orion's sword is referenced in the song "The Dark of the Sun" by

Tom Petty Thomas Earl Petty (October 20, 1950October 2, 2017) was an American singer, songwriter, and musician. He was the leader and frontman of the Rock music, rock bands Tom Petty and the Heartbreakers and Mudcrutch and a member of the late 1980s sup ...

on his 1991 album ''

Into the Great Wide Open ''Into the Great Wide Open'' is the eighth studio album by American rock band Tom Petty and the Heartbreakers. Released in July 1991, it was the band's last with MCA Records. The album was the second that Petty produced with Jeff Lynne, followin ...

'', in the line "saw you sail across a river underneath Orion's sword ...". It is also mentioned in Jethro Tull's song "Orion", on their 1979 album ''Stormwatch'', in the lines ''"Your faithful dog shines brighter than its lord and master, your jewelled sword twinkles as the world rolls by."''

Gallery

References

{{reflist, 25em Orion (constellation) Asterisms (astronomy)