Name:
ORION
Translation:
Orion, the hunter
Abbreviation:
Ori
Region:
Equatorial
Located between:
Taurus, Eridanus, Lepus, Canis Major, Monocerus and Gemini
Right Ascension (RA):
4h 40m to 6h 20m
Declination:
-8deg to +23deg
Season:
Winter
Midnight culmination:
December 13
Mythology:
Every culture has its own constellations’ names and mythology. Constellations rarely look like the object their name suggests and many groupings of stars have been called different things over the years.
According to Greek mythology, the stars in this region of the sky are labeled Orion in honor of a great hunter, son of Neptune and the nymph Eurayle. It’s the most spread myth about the constellation. The drawing below, from E. Burritt's atlas of 1835, shows the typical image of Orion - club in hand, lion-skin shield, attacking the bull, Taurus.To the Egyptians, the same stars were a tribute to the god of light, Osiris. The pharoahs, so it was believed, began their journeys in the celestial realms with a visit to Osiris and Isis in the regions of Orion and Sirius. Other cultures saw such things as a turtle or octopus. Some cultures combined these stars and others into larger figures like a Cayman or alligator-like creature. Others saw subsets of the stars as individual figures.
Description:
Three stars in a row make up Orion's belt, within a rectangle of four bright stars representing his shoulders and feet. The sword hanging from his belt includes M42, the beautiful Orion nebula. Since Orion's belt of three bright stars lies upon the celestial equator, Orion is visible from every inhabited part of the globe. Orion the hunter appropriately faces the red eye of Taurus. His two hunting dogs follow behind: The Big Dog or Canis Major, with the bright star Sirius. And the Little Dog, or Canis Minor, with the bright star Procyon.
Legend: In the constellation chart above...
1. Star colors represent their spectral types (even for double stars).
2. Bright star labels are yellow; significant other stars are labelled in magenta.
3. The size of each star indicates its relative magnitude.
4. Constellation names are light blue.
5. Grid lines represent either 10 degree intervals of declination above or below the equator, or intervals of one hour (=15 degrees) of right ascension (measured along the equator).
6. Messier object numbers are pink.
9. Open clusters are dotted white circles.
10. Bright nebula are magenta squares.
Special Stars
Orion's right shoulder, alpha Ori (Betelgeuse), is a variable red giant; its brightness varies from 0.4 mag to 1.3 mag with no set period. It belong to the 20 brightest stars in the sky. During it pulsations the diameter of the star varies from 300 to 400 times the diameter of the sun. If Betelgeuse were our Sun, its surface would reach beyond the orbit of Mars! Bluish Rigel is Orion's left foot, the 7th brightest star in the sky (0,08 mag).
Nebulae
1. M42, Orion Nebula (Diffuse nebula), 4,0mag. A sword hanging from his belt at first sight looks like three stars, but the middle one is ill-defined. With binoculars you can tell that it is not a star, but a cloudy region, called the Great Orion Nebula. A powerful telescope reveals the nebula to be a giant cloud of luminous gas, a cosmic nursery where stars are now being born. Through the Hubble space telescope the Great Orion Nebula becomes a colorful and awesome spectacle, over 20 000 times larger than our solar system.
2. M43 (Diffuse nebula), 9.0 mag.
3. M78 (Diffuse nebula), 8.3 mag.
