This time of year if you look to the south just after it gets dark, and you have a clear horizon, and you are not in a big city with too much light, you can see the constellation Scorpius, the scorpion. From mid-Northern latitudes it is just above the horizon for a couple of hours before it sets. It is one of my favorite constellations because it actually looks rather like its namesake and because some of the richest parts of the Milky Way lie in Scorpius.
I have attached four photos for you to enjoy, all in Scorpius. In each photo north is to the top. First is a wide angle view of the whole constellation, and I have added green lines between the prominent stars that make the shape like a scorpion. (Ignore the yellow rectangle for now.) At the top right are three stars that represent the head. The body then curves down and to the left until it curls upward to end in two stars side-by-side that represent the stinger. Notice that this image, especially in the left half, is filled with star clouds and dark lanes of the Milky Way. These are readily visible to the naked eye if you have a really dark sky. The brightest star in Scorpius is Antares, located inside the yellow rectangle.
The second image is of the area inside the yellow rectangle. I have left off the green lines showing the scorpion shape, but I have labeled Antares so you can tell it from other bright blobs in the region. Antares is a red supergiant star. It is so large that if it replaced the sun, it would extend all the way out past the orbit of Mars, completely engulfing the earth. This image was exposed for about an hour, six times as long as the previous one, so it goes much deeper, making the faint nebulosity in the region look very bright. Although most red nebulae consist of hydrogen gas energized by nearby stars to emit red light, the yellowish-reddish nebulosity just above Antares is probably a dust cloud of solid particles that are simply reflecting the red light of brilliant Antares, which is embedded in it. The bluish nebulosity is light from blue-white stars reflected off of nearby interstellar gas and dust. The narrow green rectangle in this photo shows the area captured in the third image.
The tall thin image is actually two one-hour images, one just north of the other, stitched together to make a single image. By enlarging this image and looking at one section at a time, you can see more detail in the gas clouds and in the dark clouds of dust that obscure the stars behind them. Near the top is the bright star (actually 3 stars close together) Rho Ophiuchi. It is surrounded by the large blue reflection nebula IC 4604. This is a region of much new star formation, intensely studied by professional astronomers. Moving south from there we come to two stars close together surrounded by a bright whitish nebula with dark lanes swirling through it. This nebula is known as IC 4603. A little below it near the right edge of the frame is a rainbow looking arc of red and green light. This is an optical artifact resulting from scattered light from a bright star just outside of the picture. Continuing further down we come to a large yellowish-reddish patch. This is a small part of the large dust cloud, IC 4606, that extends all the way over to and around Antares, which is out of the picture, down and to the left. In the lower, more yellow part of this cloud is a small globular star cluster known as NGC 6144. And finally at the bottom edge and to the right is the large globular cluster known as M 4. These two objects are not part of the mass of nebulosity in this region of our galaxy. Rather they are two of the roughly 150 globular clusters — spherical, tightly packed clusters of tens to hundreds of thousands of very old stars — that surround our galaxy.
And finally the fourth image is a more magnified image of just the globular cluster M 4. This is one of the closest globular clusters to us, being about 7000 light years away. (The smaller appearing NGC 6144 is about 4 times farther away, and the colored nebulae in the earlier images are only 400 to 600 light years away.) A single planet has been detected around one of the stars in M 4. This is very unusual because planetary orbits are unstable in the star-crowded environments of globular clusters. M 4 is a beautiful sight in a moderate-sized telescope, where one can note its distinctive north-south line of stars that run through its very center. … That’s as up close as I can get you with the photographic equipment I have, but the constellation of Scorpius is filled with many more wonders.
Keep looking up,
Carter, (sometime) Resident (amateur) Astronomer,
Lookout Observatory
