Dan Pope

Among the oldest legends, the Sumerians saw their god of war, Nergal, with a bow an arrow in the stars of Sagittarius (saj-ih-TAIR-ee-us), the Archer.  Later the Greeks saw a Centaur (torso of a man – body of a horse) with a bow and an arrow aimed at the heart of the Scorpion.  Sagittarius is a member of the Zodiac and so is very near the Ecliptic, the plane of our Solar System.  Over time, the Sun, Moon, and planets all appear to pass through the Sagittarius part of the sky.

It is difficult to see the images that the Sumerian and Greek legends imply in these stars.  Within the Sagittarius constellation, there are 8 stars above the southern horizon known as the Teapot, which makes it easy to find in the summer night sky.  The handle is on the left with the spout on the right and a pointy lid on the top.  To get an idea about the size of the group of stars we are looking for, hold your fist at arms length and you will just about cover the Teapot.  As the night progresses the Teapot will appear to be tilting spout down toward the southwest as though pouring.  If you have a reasonably dark sky you will be able to see what looks like a slight haze surrounding the Teapot and especially just above the spout.  This haze is not a cloud in Earth’s atmosphere but rather it is the light from millions of stars in the Milky Way that our eyes are unable to resolve into individual points of light because they are so far away.  If you have binoculars you will be able to resolve some of the haze into individual stars but most will remain a blur for you.

The area just above the spout is the Great Sagittarius Star Cloud.  At the very tip of the spout is an area known as Baade’s Window, as in a window through the interstellar gas and dust clouds blocking our view. Another naked eye object is the Lagoon Nebula, M8, just 5,000 light years away.  Above and to the left of the Lagoon Nebula, about a closed fist at arm’s length, is the Small Sagittarius Star Cloud, M24.  The stars in M24 are 16,000 light years away.  We are seeing the light from stars that are more than half way to the center of our home galaxy.  When we look less than a closed fist at arm’s length to the right of the spout we are looking toward the very center of our Milky Way Galaxy, marked ‘GC’, Galactic Center.  Interstellar gas and dust clouds block our view, in the visible light range, in this direction.  If our view were not blocked we would see a brighter dome of light to the right of the Great Sagittarius Star Cloud.  X-ray, infrared, and radio telescopes are able to ‘see’ through the interstellar gas and dust and have provided astronomers with a view of the stars near the center of our galaxy. Astronomers now know there is a great concentration of stars at about 27,000 light years in this direction.  They also have evidence that a Black Hole exists at the very center of our galaxy.  A Black Hole is a concentration of mass so dense that nothing – not even light – can escape its gravitational pull once swallowed up.

To the lower right of Sagittarius is Ptolemy’s Cluster, M7, an open or galactic star cluster about 800 light years from us.

Just to the upper left of the lid star is the Sagittarius Cluster, M22, a globular star cluster.  At 10,000 light years it is one of the closer globular star clusters.

The above objects can be observed with the naked eye but you might need to use averted vision, looking slightly to one side of the object. They will appear as small fuzzy patches or ‘brightnings’ in the Milky Way. If you have binoculars you will be able to see several more nebulae, open star clusters, and globular star clusters in this direction.

The French astronomer Charles Messier (MESS-ee-ay or mess-ee-AY) (1730-1817) created a catalogue of dim or diffused objects that he observed. Subsequently, those who created star charts identified these objects by listing them with the letter ‘M’ followed by the number from Messier’s catalog.

The full Moon in August is known as the Green Corn Moon or the Grain Moon.

I have been enjoying watching Venus, Mars and Saturn, as they have been moving closer together above the southwestern horizon.  I hope Friday the 13th is a clear night since our Moon will then join the group for added enjoyment. I’ll stay up until our Moon sets in hopes of seeing a few more meteors from the Perseid Shower.

Next week we will dwell more on Venus, Mars, and Saturn before that close gathering disappears below our western horizon.

Clear skies.