A Different View of a Familiar Skyscape

February 25, 2020  •  Leave a Comment

Since ancient times, Orion (the Hunter) has been one of the most familiar and recognizable constellations in the winter night sky. In this photo, Orion is at upper right, defined by four bright stars in a rough rectangle with three more stars known as Orion's Belt in a row in the center of the four corners, and a fuzzy patch below called the sword. The bright star below and to the left of Orion is Sirius in the constellation Canis Major (the Big Dog), the brightest-appearing star in the sky. Farther to the left is part of the Milky Way, composed of many stars, part of the disk of the Milky Way galaxy. This photo was taken on a particularly clear, moonless night in Yellowwood State Forest in Brown County, Indiana overlooking Yellowwood Lake. 

Starry Night over Yellowwood LakeStarry Night over Yellowwood Lake

This part of the sky holds secrets that we cannot see with naked eyes, even on the darkest nights and clearest skies. Some of these secrets involve light emitted by hydrogen atoms in great clouds of gas and dust (technical term: nebulae) in between the stars in our galaxy. We can see the brighter stars, but much of the light emitted by the clouds of hydrogen is too red for our eyes to see. Even most cameras cannot record this light because they include a filter that blocks infrared and far red light. Recently I had one of my DSLR camera bodies modified to swap out the infrared-blocking filter to one that transmits the hydrogen light. Using long exposures, and a bit of post-processing, these vast clouds of gas become visible. This is a close-up of the upper right area in the first photo showing mostly only Orion and the neighboring Monoceros constellations.
Orion & MonocerosOrion & MonocerosA composite of eight exposures, 1 minute each with a Nikon D800 converted to record the light of hydrogen and 50mm f/1.8 lens on an iOptron SkyGuider Pro mount to keep the camera pointing at the same spot in the sky. Many large clouds of glowing gas in our galaxy are in this field: the Great Nebula in Orion (M42) in Orion's sword and Horsehead and Flame Nebulae just above in the belt are dwarfed by the much wider Barnard's Loop to the left and another large feature above. The fine Rosette Nebula is to the upper left and above another large complex including the Cone Nebula and Christmas Tree Cluster. Anyone very familiar with Orion will notice that one of his brighter stars, Betelgeuse (Alpha Ori) is dimmer than usual these days. It is known to be variable, but this is the dimmest it has been for quite a while and nobody is sure why. Stay tuned.

The brightest patch, the Great Nebula in Orion (M42), part of Orion's sword and the Horsehead and Flame Nebulae just above in his belt are dwarfed by the much wider Barnard's Loop to the left and another large feature above. The fine Rosette Nebula is to the upper left and above another large complex including the Cone Nebula and Christmas Tree Cluster. Anyone very familiar with Orion will notice that one of his brighter stars, Betelgeuse (Alpha Ori) is dimmer than usual these days. It is known to be variable, but this is the dimmest it has been for quite a while and nobody is sure why. Stay tuned.


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