The Zodiac --- The Constellation of Sagittarius the Archer

Sagittarius has many stars, and since it is superimposed on our view of the Milky Way, just which stars "belong" to Sagittarius and which don't is something of an open question.

Sagittarius is the ninth constellation of the Zodiac. Called "The Archer" or "The Centaur" Sagittarius doesn't much look like an asterism of anything, and astronomers aren't even agreed upon which stars make up the asterism itself. The most definitive part of Sagittarius is the portion called "The Teapot" (or "The Milk Jug") which looks like it is pouring the stars of the Milky Way from its spout. 

The "Teapot Asterism" is the heart of Sagittarius. Some of the many nebulae "in" Sagittarius can be seen here. Note the stream of stellar "milk" pouring from the spout.

 

The first definite record of Sagittarius comes out of Sumer. Lapis Lazuli-colored Nunki (see my post on this star, the 50th star of the Nautical Almanac) was the patron star of Eridu, their most ancient metropolis. There's also evidence that the Sumerians linked Kaus Australis (Number 48) the brightest star in Sagittarius, to the birth of the star-stream of the Milky Way. Otherwise, Sagittarius is not a particularly prominent constellation.

"The Teapot."

As for the constellation itself, the early Sumerians considered it to be Nergal the god of the Underworld --- who was also represented in two aspects by Gemini. Nergal (despite his identification with war, death, pestilence, and other calamities) was seemingly a rather benign god in practice, and clearly very important --- especially since Nunki was his most prominent star. 

Sagittarius has been many things over the millennia --- god, guardian, and mentor.

Later Sumerians called the figure Pabilsag, "The Chief Ancestor" and may have considered themselves as descended from this creature, which resembled a winged human-headed lion or sphinx. 

The Greeks called the constellation Chiron after the wise centaur who tutored Jason, leader of the Argonauts, but some sources claim that the constellation Centaurus is Chiron and that Sagittarius is Crotus, the inventor of archery. 

The Romans called him Sagittarius, and his arrow targets Antares. According to the Roman mythology, Sagittarius will kill the Scorpion sent to kill Orion. 

The Sagittarius Arm of the Milky Way as seen from this planet.

Sagittarius is superimposed over the densest portion of the Milky Way. Thus, Sagittarius is home to thousands of deep sky objects, including nebulae, globular clusters, and whole star families. It is also the (apparent) region of the Sagittarius Arm, one of the arms of the Milky Way, which is a barred spiral galaxy. 

The Red Spider Nebula.

NGC 6559, a star nursery about 5000 light years from Earth.

The Trifid Nebula, M20 or NGC 6514.

 

Sagittarius is the region of the Galactic Center (of the Milky Way), the densest region of stars in our galaxy. There is a supermassive black hole region at the center of the Galactic Center.

Sagittarius A* . Looking toward the dense Galactic Center. The less-dense region to the lower right marks out the Supermassive Black Hole at the heart of the Milky Way.

The very powerful and very bright radio source called Sagittarius A* is very near the Galactic Center. It is part of a more diffuse but still dominating stellar grouping called Sagittarius A, subdivided into Sagittarius A East and Sagittarius A West. 

A map of the Milky Way, showing the relative position of our Sun and its solar system.

It was from this general region that Earth received the WOW! signal on August 15, 1977. A powerful burst of radio emission in a band previously determined to be likely for extraterrestrials to use, WOW! has not been heard again.

The WOW! signal. Proof of intelligent extraterrestrial life, or just an anomaly?