Orion constellation
Orion (the Hunter) is a constellation on the celestial equator, best seen in the evening in January. Its brightest star is Rigel (magnitude 0.12). It contains Orion's Belt. Orion covers 594 square degrees and is the 26th-largest of the 88 constellations.
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How to find Orion, step by step
Start with the three stars of the belt.
- On winter evenings (December to March) look south for three bright stars of similar brightness in a short, straight row: Orion's Belt.
- Above the belt, on the left, is orange-red Betelgeuse, the hunter's shoulder.
- Below the belt, on the right, is blue-white Rigel, his foot. Rigel and Betelgeuse together with Bellatrix and Saiph frame the hourglass shape.
- Below the belt hangs a short line of fainter stars, the sword. Its middle "star" is the Orion Nebula (M42), a fuzzy patch even in binoculars.
Orion or Orion's Belt?
Orion's Belt is only the row of three stars (Alnitak, Alnilam and Mintaka) in the middle of the constellation. Orion is the whole figure of the hunter: the belt, the shoulders Betelgeuse and Bellatrix, the feet Rigel and Saiph, the sword and the raised club.
Detailed star map of Orion
Facts
| Latin name | Orion (genitive: Orionis) |
|---|---|
| Abbreviation | Ori |
| Meaning | the Hunter |
| Area | 594 square degrees (26th of 88) |
| Location | right ascension 5.6 h, declination +7° |
| Visible from | latitudes 79° N to 67° S (whole constellation) |
| Best month | January (at about 9 pm) |
| Brightest star | Rigel |
| Stars brighter than magnitude 6 | 128 |
| Named stars (IAU) | 10 |
| Messier objects | M42, M43, M78 |
| Neighbors | Eridanus, Gemini, Lepus, Monoceros, Taurus |
How to find Orion
From 40° N (the USA, southern Europe, Japan) look south in January evenings: at about 9 pm Orion stands highest, around 57° above the southern horizon. From 35° S (Australia, South Africa, Argentina) it is highest in the north, about 48° above the horizon. The months before and after (December and February) are also good: then it is up a couple of hours earlier or later.
Orion borders Eridanus, Gemini, Lepus, Monoceros and Taurus.
Asterisms with stars in Orion: Orion's Belt, Winter Triangle, Winter Hexagon.
Stars of Orion
Orion has 128 stars brighter than magnitude 6, the limit of the naked eye under a dark sky. These are the brightest:
| Star | Designation | Magnitude | Type | Distance |
|---|---|---|---|---|
| Rigel | β Orionis | 0.12 | B8Ia: | 860 ly |
| Betelgeuse | α Orionis | 0.5 | M1-2Ia-Iab | 548 ly |
| Bellatrix | γ Orionis | 1.64 | B2III | 395 ly |
| Alnilam | ε Orionis | 1.7 | B0Ia | 1,194 ly |
| Alnitak | ζ Orionis | 2.05 | O9.7Ib | 969 ly |
| Saiph | κ Orionis | 2.06 | B0.5Ia | 799 ly |
| Mintaka | δ Orionis | 2.23 | O9.5II | — |
| Hatysa | ι Orionis | 2.77 | O9III | — |
| Tabit | π3 Orionis | 3.19 | F6V | 26 ly |
| — | η Orionis | 3.36 | B1V+B2e | — |
| Meissa | λ Orionis | 3.54 | O8III((f)) | — |
| — | τ Orionis | 3.6 | B5III | — |
Deep-sky objects in Orion
Orion contains 3 objects from Charles Messier's catalog:
- Orion Nebula (M42): emission nebula, 4.0 mag
- De Mairan's Nebula (M43): emission nebula, 9.0 mag
- Messier 78 (M78): reflection nebula, 8.3 mag
Printable Orion map and outline
A black and white version for printing and a plain outline of the Orion figure, useful for school projects, worksheets and learning to recognize the shape.
History
Orion is one of the 48 constellations listed by Ptolemy in the Almagest (2nd century AD). Its official boundary was drawn by Eugène Delporte for the International Astronomical Union in 1930.
Questions about Orion
What is the brightest star in Orion?
Rigel, at magnitude 0.12, about 860 light-years away.
When can you see Orion?
Orion is best seen in the evening in January. The whole constellation is visible from latitudes between 79° N and 67° S.
How many stars are in Orion?
128 stars in Orion are brighter than magnitude 6 and can be seen with the naked eye under a dark sky; 10 of them have official IAU names.
What does Orion mean?
Orion means “the Hunter” in Latin. Its abbreviation is Ori and the genitive, used in star names such as β Orionis, is Orionis.
