The most distinctive constellation in our sky is that of Orion the Hunter. In the months between November and March, the Hunter travels across the heavens in search of the mythological game with his two canine companions.
The constellation is located slightly north of the ecliptic, with a notable rectangular shape with its distinctive narrowing in the centre formed by the three bright stars. Ancient Greek astronomers depict this combination of stars as Orion’s belt from which his warrior sword hangs. In the Southern hemisphere, the constellation is more easily recognised as a saucepan and handle, due to the inverted perspective to that of the Northern hemisphere.
In ancient Greek Mythology, Orion is a handsome giant and might hunter, son of Neptune. He could wade through the oceans and pass over mountains to reach his destination. Orion lived with the archer-goddess Diana, sister of Apollo who disapproved of their relationship. The ancient fables say that Apollo Teased sister Diana that she was not good enough to hit a target at sea. He pointed to a small distant object many fathoms away, and asked her to draw her bow and strike it with her arrow. Diana not realising the object was Orion returning from his hunt, killing him with one shot. Diana placed Orion amongst the stars holding his arched bow, carrying his golden sword and club, whilst wearing the skin of a lion. His two dogs, Sirius following behind, and Pleiades leading him in his hunt throughout the night.
In another mythical tale, Orion is killed by the sting of the scorpion which is why Orion and Scorpius do not share the sky together. The constellation of Orion sets in the west as Scorpius rises in the east.
The brightest star in the Orion constellation is Beta Ori β (Rigel) representing the hunters leg. This star is a blue-white in colour being a supergiant with a magnitude of 0.1 . Alpha Ori α (Betelgeuse) is the giants shoulder formed by a variable red supergiant at a magnitude 0.0 to 1.3 . To the naked eye this star is easily discerned by its red colour, a vivid contrast to the brilliant white stars around it.
The belt around Orion’s waist includes Delta Ori δ (Mintaka) a 2.2 mag. multiple star. Through binoculars or a small telescope, you will see an unrelated companion star of 6.9 mag. The central star of the three in the belt is Epsilon Ori ε (Alnilam) being a 1.7 mag. blue giant. Zeta Ori ζ (Alnitak) is the third star in the belt shining at 1.8 mag. with a 4.0 mag. companion which can be resolved with a 75mm (3”) telescope.
The most impressive region in the Orion constellation is M42 (above on the right side of the picture including M43 on the left side of the picture), The Great Orion Nebula at mag. 3.7 . This object is a large hydrogen cloud where the gas swirls around condensing into thick clusters. These dense nebulas are the result of super nova that explode leaving rich fields of gas that produce new stars. This nebula is found in Orion’s sword as it dangles from his belt. Visible with the naked eye, it appears as a fuzzy star close to the tip of the sword. Viewed through binoculars or a telescope it reveals an impressive swirl of gas with glimpses of stars forming in its centre.
The stars located in the heart of M42 are known as the Trapezium designated as Theta 1 Ori θ1. (see diagram) Depending upon the size of your telescope will determine how many stars you are able to see. Using a 4” (105mm) refractor the brightest star at the top is labelled “C” with a mag. of 5.1; “A” is an eclipsing variable mag. 6.7 – 7.7; “B” is mag. 8.5; “D” mag. 6.6; with “E” & “F” mag. 10 . These stars are only 1 million years of age, perhaps the newest stars in our sky. Four stars are easily found in the Trapezium with a small telescope with five star, the fifth star very faint, seen in a 78mm refractor at 126x magnification and good seeing conditions. With a 6” telescope six stars “F” can be seen although faint at 10 or 11 mag. Located near the brighter star “C” the contrast can create a problem separating them without masking. The darker your sky the better you are able to resolve the different stars.
M43 is also part of the same gas cloud located left of M42 in the picture above separated by a dark lane of dust known as the Fish mouth. This wedge of nebulosity surrounds a 7th mag star called Bonds Star.
The well-known Horse Head Nebula is often immortalised in pictures related to the Orion Nebular. In reality, this is an extremely small section of a very large nebula. It is found south of Zeta Ori sitting in front of a bar nebulosity IC 434. You will need a large telescope with high magnification to clearly resolve the image. Mush better in the Hubble pictures with its bright red coloured gas and contrasted background.
Sigma Ori ς is a blue white star worth looking for. Visible with the naked eye, a small telescope will reveal two companion stars of mag. 6.7 & 6.6 on one side of the field and the third companion in the other side at a 9th mag. There is some resemblance to that of a planet and its satellite moons.
M78 – NGC 2068 (right side of picture above) is a small elongated nebula on the same parallel as Delta Ori (Mintaka)in the belt. This object is mag. 8 and should be visible in 3” telescope or a pair of 7 x 35 binoculars. This reflection nebula surrounds a pair of 10th Mag. stars. Viewed through an 8” telescope at low magnification (40x) a bright nebulosity with two bright stars is seen, but with high magnification the detail is improved to shown more stars. This could easily be mistaken for a comet with its brighter nucleus and tail of gas. Other fainter objects can be found near M78 including NGC 2071 (seen on the left side of picture above), NGC 2064 and NGC 2067.
In the picture above we see a bluish M78 (center) embraced in dark, dusty clouds, along with a smaller reflection nebula in the region, NGC 2071 (top). Yellowish and even more compact, the recently discovered, variable McNeil’s Nebula is prominent in the scene below and right of center.
McNeil’s Nebula with its illuminating young star at the tip, do not appear in images of the area before September 2003. The emergence of McNeil’s Nebula is a rare event to witness and astronomers are eagerly following its development. The Orion nebula complex itself is around 1,500 light-years away. At that distance, the above image spans less than 10 light-years.