Spectacular Sagittarius


The arms of the Milky Way are named for the constellations they pass through: Perseus, Sagittarius, Centaurus and Cygnus are the major arms. Sagittarius is the most spectacular because the center of the Milky Way lies behind it, and that's where it's the densest and brightest.

You may recognize Sagittarius at the Teapot asterism. Look to the south and you will see the Teapot in the Milky Way sitting close to the horizon with the handle on the left and the spout on the right. The Milky Way appears to be steam coming up from the Teapot!

The actual constellation is Sagittarius the Archer with its bow aimed west towards Scorpius, the scorpion. Scorpios has a distinct "J" shape also described as a fishhook. The bright orange star Antares lies in the long arm of the "J". The Sagittarius arrowhead is the tip of the Teapot sprout. The Archer is pictured as a centaur creature with the upper torso of a man and the body and legs of a horse. While you're looking at the Teapot, see if you can identify the Archer. 

Many constellations are difficult to identify. When the ancient Greeks and other civilizations first named them more than 2,500 years ago there were no lights. So even the fainter stars were easy to see. Now we can't see as much, plus many stars have changed position in relation to Earth and the constellations no longer appear to be the same image they were back then. That's why asterisms have become more common and easily identifiable.

In that area you should also be able to see four "naked-eye" star clusters. They may just look like fuzzy blobs in the sky. Binoculars will clarify the blob and identify the stars. They also help you to see more of the clusters.

Star clusters are groups of stars that are sometimes quite dense while others are more openly scattered. 

Some may glow more because they contain a lot of gas and dust which reflects more light. They are consolidated toward the galactic center where most stars are born in clusters of tens to thousands in the great dark clouds that permeate space.