More Backyard Astronomy 12/13/2020. There it is! It's Messier 42, the Great Nebula in the Constellation of Orion the Hunter. This beautiful nebula can be seen through a small telescope or binoculars. It is found in the middle star of the sword of Orion. This is my first photograph of M42 this fall season. For those of you that do not understand what you are seeing here, this is an enormous cloud of interstellar gas and dust. It is made up of hydrogen and oxygen gases which are emitting light, glowing from ultraviolet energy coming from nearby hot bright stars. In fact this cloud of gas is so dense that stars are forming within this cloud almost like dew drops. This is a large star forming region containing hot new stars, some just 10,000 years old (and probably feeling my age).

At a distance of just 20 years, traveling at the speed of light, Messier 42 is nearly on top of us. It is also one of the brightest nebulas closest to earth. M42 is also about 24 light years across. I photographed the nebula using my Hydrogen (Ha) and Oxygen (Ox III) filters. The red areas are predominately hydrogen, and the bluer areas are the oxygen.

Some photographs of M42 and other nebulas show a tint of green. Green is actually pretty rare. Astronomers saw the green in their spectrographs but couldn't figure out what element was putting out that green. These early 19th century scientists couldn't duplicate the phenomenon in a laboratory. So named the mysterious element, Nebulium. They had a chance to name it Kyptonite but missed it.

With better labs and understanding of nuclear physics, more recent scientists found that the green spectral line was just doubly ionized oxygen which can be made in the vacuum of space. Sometimes a friend will ask me how dense if that nebula? Is it like fog on my driveway? The answer is kind of a shocker. A dense region of gas in space is simply a molecule or two per cubic foot. That is how foreboding the void of space really is. Looking at 24 light years of glowing molecules looks like a pretty dense cloud.

This photograph was made from 15 four minute exposures each of hydrogren and oxygen stacked one on top of another. I had taken a few more exposures but when I went to process them I found that a small frond from my neighbor's palm tree had ruined them. Some of the stars looked like footballs with points on each end. Hopefully, I will have another clear(er) night and can gather more exposures and do this again.

Hope you liked my photograph. Happy Chanukah and a Merry Christmas to all my friends.

Clear skies to you! Ken Adler-