Sunday, December 19, 2004

some stellar observations

It's a nice, clear night here in Alabama, which inspired me to break out the binoculars and scan the sky. Living in the city, I have to deal with a certain amount of light pollution, which wasn't too bad at 0030, since most of the city had gone to bed. Orion was high in the southern sky, with the Great Nebula in Orion just visible to the naked eye. I have a pair of 10x50 Bushnell binoculars, which aren't too bad for city viewing. With naked eye, the sword of Orion was visible as 2 "stars". With the binoculars, I was able to resolve the Trapezium at the end of the sword, as individual stars. M42/M43 appeared to be a single brightly glowing area that is most definitely not a star.

photograph of the Constellation Orion
The constellation Orion, the Hunter.

Reflection Nebula in Orion's sword, NGC 1973-75-77
The top "star" in the sword of Orion, the reflection nebulae NCG 1973-75-77.

The Great Nebula in Orion, M42/43
The middle "star" in Orion's sword. Messier 42 is the large pink nebula in the center, M43 is the small nebula just above M42.

The Pleiades, M45, was another object that was easily viewed from the city this morning. With the naked eye, I could resolve 4-5 stars of the cluster. With the binoculars, I was able to see about 9 stars, the main named stars of the cluster, which were distinctly bluish. I am not able to say for certain I could see any of the reflection nebula around the cluster. I was not able to hold my hand steady enough to get a clear view of that type of detail.

photograph of the Pleiades, M45.
Photograph of the Pleiades and the nebulosity. Image with the names of the major stars.

Quick overview on nebulae and the colors. Red/pink nebulae, called Emission Nebulae, are from hydrogen ions being excited by energy from stars in the nebula, causing the hydrogen to emit the red/pink light we see in photograph. Blue nebulae, Reflection Nebulae, are caused by dust around stars scattering the light. This is the same thing that happens with smoke, which is why it appears bluish, and the Earth's atmosphere scatters light from the sun, causing the sky to appear blue. Wikipedia has a good article on nebulae, if you want a more detailed explanation of the colors.

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