September 2013

Tony Martinez

                                    Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections; what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on September 5th. For September, your best viewing nights will be from September 1st to the 10th, and September 25th to the 30th. The Star chart below is set for Florence, SC on September 15th at 9 pm.


Constellation Focus:
A few months ago I discussed another type of night viewing plan; the constellation plan. The object is to pick an easily visible constellation, and spend most of your viewing time only in that constellation. Of course most constellation plans are seasonally directed. This month let’s try to focus on the constellation Sagittarius. Although Sagittarius is moving low into the southwest, it is still a good target between 9 and 10 pm each night.

First let’s begin with a naked eye view of Sagittarius. As we notice with many constellations, what the ancient people saw in the sky often does not match what we see. The constellation Sagittarius does not look very much like an archer/horse (Centaur).


However, the main stars do look like a common object found around the house; a teapot.


You may also notice that this teapot asterism overlays the Milky Way, as do several other constellations. However, Sagittarius overlays the Milky Way close to our galactic center. Evidence supports the theory that all spiral galaxies contain a Black Hole at their center. Using radio astronomy, scientists have located the position of the Black Hole in the Milky Way. Our Black Hole is called Sagittarius A* (pronounced “Sagittarius A-star). Now, continuing on your naked eye observation of Sagittarius, you can use the “teapot” to find the location of Sagittarius A*. Look at the teapot and imagine it sitting on a stove, and boiling. Where the steam would be above the spout is the location of the center of the Milky Way Galaxy and our Black Hole, Sagittarius A*; marked below by the red “star” below.


I won’t go over all the common names of the stars in the Teapot asterism, but the brightest star does have the euphonious name; Nunki.

Next you should scan Sagittarius with 7 to 10 power binoculars.  Note:  All of the constellations have been given official boundaries, and these fit together like pieces of a puzzle; see example below.


So if the location of a particular Messier Object was assigned a constellation name, it would be found somewhere within the official boundary of that constellation. Within the boundaries of Sagittarius are 15 Messier objects. This is the largest number of Messier Objects found in any constellation. Therefore, if you wish to add 15 Messiers to your list, carefully scan Sagittarius. The image below shows the locations of the 15 Messiers within the white boundary of Sagittarius. These Messiers are shown as yellow circles and green squares.


Anyone who has taken my earlier suggestion to try to locate all 110 Messier Objects has realized that many Messiers can be quite challenging to locate. Sagittarius contains Messiers that range from easy to very difficult.  You also may have to brace your binoculars on a building or car to maximize your chances for finding the small and dim Messiers.

The most interesting Messier in Sagittarius is also the easiest to find; M22. M22 is a globular star cluster, and is one of the two best in the northern hemisphere, the other one being M13 in Hercules. If you aim your binoculars at the top star of the teapot, M22 will be in your field of view above and to the left. In the same field of view to the right is M28, but unless you are in a very dark viewing site, you will not see it. In addition to M22, the easiest Messier Objects in Sagittarius are M8, M17, M18, M23, M25, and M55.  The most difficult Messiers in Sagittarius are M20, M21, M54, M69 and M70.

Sagittarius gives a unique opportunity to test out various dark sky viewing sites in the area. Think about places you can safely go to view the stars in our area. You can start with your own backyard. If you have friends in the rural outskirts of Florence, check their locations out. With permission, you may also be able to use Lynches River Park. By using 7-10 power binoculars only, you can easily drive from site to site in one night, if you choose, without the necessity of setting up a telescope.

Although binocular viewing does allow for easy no setup viewing, some amateurs do use various tripod setups to aid their viewing.

Although I usually mention using 7 and 10 power binoculars because they can be hand held, if you decide to use tripod setups, you should consider purchasing larger binoculars. What few people realize is that you can purchase a good pair of 15 X 70 mm binoculars for only $89; example, Orion Telescopes, on-line. Also, larger binoculars will greatly help your Messier search.

Finally, your visit with the constellation Sagittarius should end by observing M22 with a telescope. Through binoculars, M22 will look like a smudge, but through a telescope, you may be able to resolve some individual stars, Globular star clusters are fascinating objects. Whenever I view them through a telescope, I always imagine what the night sky would look like living on a planet circling one of the stars in a globular cluster.  Below is Messier 22.


Naked Eye Sights: The constellation Sagittarius. The Teapot Asterism. The location of our Black Hole

Binocular Sights (7 to 10 power): See how many Messier Objects you can find.

Telescope Sights (60-100mm): Messier M22; try to resolve some of the stars.

See you next month!


Comments are closed.