Constellation - Orion

Constellation - Orion


Orion


Orion, the Hunter is one of the most easily recognisable constellations. It sits on the celestial equator so it is visible to both the northern and southern hemispheres. It was included in Ptolemy's constellation list and is the 26th largest constellation. In the southern hemisphere Orion's belt and sword is sometimes called the saucepan as it is viewed in the opposite direction to the northern hemisphere.

There is so much to see in Orion but a lot of the deep space objects are very faint like the Horsehead nebula. Orion is home to one of the true wonders of the night sky that must not be missed, M42, The Orion Nebula.

Although, not part of the Messier or Caldwell list covered in this guide the Running Man nebula (NGC 1977) can be found half a degree northeast of the Orion nebula. It is magnitude 7 and the dark lanes of dust create the image of a running man. Hence, the name the Running Man nebula.

The three stars that make up the belt of Orion are easy to identify. Some people advocate that the three pyramids of Giza in Egypt are an earthly representation of this asterism. The size of the pyramid relates to the brightness of the star it represents. Go and have a look at an aerial view of the Pyramids and it certainly does show the two larger pyramids in a line with the smaller third pyramid slightly malaligned just like the stars in Orion's belt.

Apart from the very distinctive three stars that make up the belt of Orion the constellation also contains two very bright stars Rigel (0.3 on the chart) and Betelgeuse (0.6). Betelgeuse is very interesting. This is a red giant star. It is so massive that if you placed it where our Sun is the edge of this star would stretch out to Jupiter. Keep a close eye on Betelgeuse as it is predicted to be the next star that will go supernova.

Orion is home to the Orionids meteor shower that peaks at about 30 per hour on the 20th October.

Mythology

Orion was said to be the son of Neptune and an incredible hunter. His escapades remain rather vague. He was said to have hunted with Artemis on Crete and may have been killed by the bow of Artemis. The other main story of his demise was said to be by the sting of the scorpion, Scorpius. Zeus placed Orion in the sky opposite Scorpius so that he can make his escape in the setting west as the scorpion rises in the east.


Take the Tour:


Number Object Description Magnitude Surface Brightness
1 M42 Diffuse Nebula 4 11
M43 Diffuse Nebula 7 13
2 M78 Diffuse Nebula 8 12


Each image is the size of a full moon for size comparison.


M42, The Orion Nebula (120')

M42 DSS

Messier 42, the Orion nebula has to be one of the most breathtaking deep space objects to see in the night sky. It resides 1,345 light years away and was first discovered in 1610 by Fabri de Peiresc. This diffuse nebula spans an area some 20,000 times the size of our solar system and is the nearest source of intense star formation to us. It is visible to the naked eye with a magnitude of 4, but M42 is so large it has a surface brightness of 11. The distribution of its light isn't uniform across the object and is mainly in the centre making this a deceiving surface brightness, as the object is much closer to magnitude 4 than 11. When looking at the Orion nebula try to observe the four stars at its centre that make up the Trapezium. You'll probably need to increase your magnification to resolve all four of them. Enjoy this rose shaped beautiful and bright nebula.


M43, De Mairan's Nebula (Close-up)

M43

Messier 43, De Mairan's nebula is separated from the magnificent M42 by a dark lane of dust. If you have found M42 you have found M43 also. It is located just north of the great nebula. It is located 1,600 light years away and was discovered in 1731 by Jean-Jacques Dortous De Mairan. The image here is a close-up of the image for M42 demonstrating the small but distinctly separated M43 nebula.




M78

M78

Messier 78 is a reflection nebula found 1,600 light years away. It was discovered by Mechain in 1780. This can be a difficult nebula to spot as it is quite small and dim. This can be made easier with a light pollution filter, especially in urban conditions. Under dark skies it is visible with binoculars.





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