Orion's Belt and nebulosity, including theFlame Nebula (left) andHorsehead Nebula (lower left) named after a relatively small dark cloud, rotated 90° somewhat resembling a seahorse
Orion's Belt is anasterism in the constellation ofOrion. Other names include theBelt of Orion, theThree Kings, and theThree Sisters.[1] The belt consists of three bright and easily identifiable collinear star systems –Alnitak,Alnilam, andMintaka – nearly equally spaced in a line, spanning anangular size of ~140′ (2.3°).[2]
Owing to the high surface temperatures of their constituent stars, the intense light emitted isblue-white in color. In spite of their spot-like appearance, only Alnilam is a single star; Alnitak is atriple star system, and Mintaka a sextuple. All three owe their luminosity to the presence of one or moreblue supergiants. The brightest as viewed from Sol is Alnilam, with an apparent magnitude of 1.69,[3] followed by Alnitak at 1.74[4] and Mintaka at 2.25.[5] The ten stars of the three systems have a combined luminosity approximately 970,000 timesthat of the Sun.
Orion's Belt appears widely in historical literature and in various cultures, under many different names. It has played a central role inastral navigation in the Northern hemisphere since prehistoric times. It is considered to be among the clearest constellations in the winter sky,[6] although it is not visible during summer, when the Sun is too visually close.
In this broader view, the belt (the line of three stars in the center) is seen in relation to nearby features in Orion.
The names of the three stars that comprise the belt derive fromArabic. All three were once known asAl Niṭhām (النظام) meaning "string of pearls" with spelling variants that includeAlnihan andAinilam,[7] which was suggested by Knobel to be mistakes in transliteration or copy errors.[8]
Alnitak (ζ Orionis) is a triple star system at the eastern end of Orion's belt and is 1,260 light-years from theEarth. Alnitak B is a 4th-magnitudeB-type star which orbits Alnitak A every 1,500 years. The primary (Alnitak A) is itself a close binary, comprising Alnitak Aa (a blue supergiant of spectral type O9.7 Ibe and an apparent magnitude of 2.0) and Alnitak Ab (a blue subgiant of spectral type B1IV and an apparent magnitude of about 4). Alnitak Aa is estimated to be up to 28 times as massive as the Sun and have a diameter 20 times greater. It is the brightest star of class O in the night sky.[9]
Alnilam (ε Orionis) is a singular B0supergiant, approximately 2,000 light-years away from Earth and magnitude 1.69. It is the 29th-brightest star in the sky and the fourth-brightest in Orion. It is 375,000 times more luminous than the Sun.[10] Its spectrum serves as one of the stable anchor points by which other stars are classified.[citation needed]
Mintaka (δ Orionis) is a six-star system at the western end of the Belt,[11] and the star system closest to the celestial equator.[7] It is the nearest massive multiple stellar system, composed of three spectroscopic components.[12] The most luminous individual star is aO9.5 II blue giant. Together, the system has a combined ~250,000 solar luminosity. Mintaka is 1,200 light-years distant, with a visual magnitude of 2.25. The innermost binary has a period of 5.732 days and a semi-major axis of approximately 32 million kilometers (0.22 AU), with the two massive stars eclipsing each other twice per completed orbit as viewed from Sol, from which regular minor dips in brightness arise.[11][12]
...those three stars of the airy Giant's zone, That glitter burnished by the frosty dark.[16]
InChina'sClassic of Poetry, the asterism, under the name "Shen" (参), was paired withAntares, which is known as "Shang" (商), to be a metaphor for two people who could never unite.[17] This might have stemmed from the observation that both Orion's Belt and Antares rise in theeast and set in thewest, but Antares only rises once Orion's Belt has set and vice versa.[citation needed]
TheMalay people refer to the Orion Belt asBintang Tiga Beradik (literally "three brother stars").[18] This constellation is often used to indicate the direction of theqibla, the Islamic direction of prayer for the people of theMalay Archipelago.[19] Like other stars, the three stars also serve as navigational guides for Malay sailors[20]
The three stars of the belt are known inPortugal andSouth America asLas Tres Marías in Spanish, and as "As Três Marias" in Portuguese.[citation needed] They also mark the northern night sky when the Sun is at its lowest point, and were a clear marker for ancient timekeeping. InMexico they are called theLos Tres Reyes Magos.[21]
TheSeri people of northwestern Mexico call the three belt starsHapj (a name denoting a hunter) which consists of three stars:Hap (mule deer),Haamoja (pronghorn), andMojet (bighorn sheep).Hap is in the middle and has been shot by the hunter; its blood has dripped ontoTiburón Island.[24]
TheMāori people of New Zealand refer to the belt asTautoru (literally "string of three"), and it is often seen as the stern of the constellationTeWaka o Rangi (the canoe ofRangi), which extends to its prow atMatariki (ThePleiades). The rising ofMatariki in the dawn sky marks the Māori New Year in late May or early June.[25]
The discredited archaeologicalOrion correlation theory postulated a connection between the positions of theGiza pyramids and those of the belt, with the linkage shown to be spurious when placed within the proper historical context.[26]
^abOplištilová, A.; Mayer, P.; Harmanec, P.; Brož, M.; Pigulski, A.; Božić, H.; Zasche, P.; Šlechta, M.; Pablo, H.; Kołaczek-Szymański, P. A.; Moffat, A. F. J.; Lovekin, C. C.; Wade, G. A.; Zwintz, K.; Popowicz, A. (24 January 2023). "Spectrum of the secondary component and new orbital elements of the massive triple star Delta Ori A".Astronomy & Astrophysics.672: A31.arXiv:2301.10290.Bibcode:2023A&A...672A..31O.doi:10.1051/0004-6361/202245272.ISSN0004-6361.
^Misran, Mahruzaman (19 September 2006).Konsep dan Penentuan Arah Kiblat. National Land and Survey Institute (INSTUN). National Land and Survey Institute (INSTUN).
