An amateur’s ramblings
No. 1 22 July 2011
This part of the sky that I am about to describe is my favorite part of the night sky. I call it the Celestial Campground, for the reasons I will give in just a few moments. First, you will need to grab a pair of binoculars and head out to a location that has a nice southern horizon. Here in Florida, the Campground rises pretty high above the southern horizon but if you live at 40 degrees North or above, this area may be a bit low in the sky for you. For the sake of space and reading, I will break the articles up into several parts. For now, let us focus on the section of the sky I love to call “The Fishhook”.
Before heading out, print out this little map:
It will help you get situated.
After you get situated and are facing south, look for a large fishhook shaped group of stars located almost due south (at 10:00pm local time). This is Scorpius. This group of stars has a bright red star called Antares (meaning rival of Mars) along with a nice pattern of blue white stars. Antares is a red giant star about 600 light years away with a radius 800 times greater than our Sun. Use this star as your staring point. On the right is an arc of stars that form the “top” of the fishhook. In astronomy books (notably Rey’s “The Stars…”) this is the location of the claws of the scorpion. We are interested in the other direct-toward the sting.
Follow the bright stars that arc south and to your left. The formation will follow a slight curve and turn back upward to a pair of stars we call the “Cat’s Eyes”. The stars mark the location of the tail/sting of the scorpion. The brightest star is called Shaula or “The Sting” (Burnham 1978). If you are located in a darker location, you will notice that Shaula is located in a bright fuzz of stars. You are looking toward the center of our galaxy-the located if the exact center is a few degrees north of the stars we are observing. If you have binoculars, look at the Cat’s Eyes and move the binos upward until you see a two tight groups of stars. One-the uppermost–should appear fuzzy, the southernmost one should be larger and have stars resolved. What you are observing are a pair of open star clusters.
The northernmost cluster is called M-6 for Messier 6, the sixth object cataloged by French astronomy Charles Messier. This cluster was discovered by de Cheseaux in 1746 and cataloged by Messier in 1764. This little star cluster is some 1 600 light years distant, though I have seen data that lists the distance as far as 2 000 light years. This little group is called the Butterfly Cluster by amateurs. Can you see the shape?
The larger cluster to the southeast is called M-7. This group is bright enough to be seen with the naked eye from a place of moderate light pollution. The distance to this cluster is about 800 light years. At that distance, the cluster will be about 20 light years across. It was originally discovered by Hevelius in 1690 but may have been observed by Ptolemy. Messier added it to his list in 1764 (Burnham 1978).
I will stop for now. Take a look around the tail end of the Fish Hook (aka, Scorpius) and soak in the view. If you do observe this, please comment about your observations! I would love to read them.
–RV 27.45 N 81.45 W
Burnham, Robert; Burnham’s Celestial Handbook, volume three. Dover Publishing, New York 1978
Rey, H.A.; The Stars, a new way to see them, Houghton Mifflin, New York, 1952, renewed 1980.