Star Clusters and Nebula
While you are looking low in the southern sky toward the center of the Milky Way, you will see many interesting objects which are only visible in the summer. The Teapot asterism, which is part of the constellation Sagittarius, sits in front of the Milky Way, and appears to be pouring tea into the tail of the constellation Scorpius the Scorpion. Scorpius sits to the right of and slightly below the Teapot and looks like a large “J” leaning to the right.
Many star clusters, clouds and nebula are visible in this area because the Milky Way center is a very active place. A star cluster is a group of stars that were born from a single interstellar cloud of gas and dust. There can be hundreds or even thousands of siblings in this group.
On a clear dark moonless night there are two clusters visible with the naked eye: the Butterfly Cluster and Ptolemy's Cluster. They are located between the Teapot and Scorpius where the tea would be pouring into the tail. The Butterfly sits above Ptolemy but is smaller and fainter because it is twice as far away from us. Without binoculars they look like fuzzy blobs, but with binoculars you will be able to see some of the stars and the shape of the cluster. See if you can figure out why the Butterfly is called that.
While you are looking in that area on that dark clear night, you should also be able to see some dark nebula. A nebula is an interstellar cloud of dust, hydrogen, helium, and other ionized gases. They clump together to form large masses, which attract more matter, and eventually become massive enough to form stars and planets. Nebula is the Latin word for cloud. Some nebulas are dark clouds, while others are bright due to stars forming deep inside with their ultraviolet radiation ionizing the surrounding gas, making it visible to us. Nebula can also be formed from massive, short-lived stars collapsing or exploding.
One of NASA’s most famous images is “The Pillars of Creation,” which is a Hubble photo of the Eagle Nebula where stars are born. Nebula are named for the objects they resemble.
If you look to the right and halfway in between the top of the Teapot and the bright orange star Antares, which is part of Scorpius near the top, you will see some dark areas in the Milky Way. These are two dark nebula that you should be able to see. This is above the two-star clusters.
The Pipe Nebula is a pipe-shaped dust lane that obscures the Milky Way stars behind it. You should be able to distinguish the horizontal pipe stem with the bowl of the pipe on the left side. The Prancing Horse is part of the Pipe Nebula. The pipe is its behind and back legs. The front legs and head are above the pipe with the back on the left side. It is like the horse is sitting on its behind waving its front legs in the air. In the southwest it is sometimes called the Burro Nebula. So go out when you can and look at the sky!