My wife and I went out last weekend to an observatory site outside of the city run by the local astronomy society. We took our amateur telescope and joined a dozen others to look at and around the constellation Sagittarius, which is located in the southern skies now.
Sagittarius, of course, is a zodiac sign, one of the twelve constellations the sun passes through in its circumnavigation of the celestial sphere. The brightest stars in the constellation form a shape that looks amazingly like a teapot. Go out tonight, if you are lucky enough to be in a dark sky area and the night isn't cloudy, and you'll see it plainly.
The region of the sky near Sagittarius is one of the richest in the night skies. Huge clouds of multicolored interstellar gas, open clusters of stars and very distant globular clusters sprinkle the area. A whole stream of these nebulae seem to rise like steam from the spout of the teapot. It's a steam cloud that stretches across thousands of light years (the distance light travels in a year at the speed of 186,000 miles a second).
The Swan Nebula is one of the treasures hidden in the great star clouds of Sagittarius. The vast blur of light looks vaguely like a swimming swan. The Swan is heated and caused to glow by a cluster of stars lying near the bright core and hidden in the cloud. There is enough matter in this wisp of celestial smoke to form a thousand solar systems such as our own.
The Wild Duck Cluster is another object everyone was looking at. It's a grouping of thousands and thousands of stars that form a shape like a wedge of flying ducks.
The globular clusters that populate the sky there are spherical groupings of stars -- sometimes millions of them -- that look like diamonds sprinkled across inky black velvet, one of the most beautiful sites eyes can gaze upon, I think. J.R.R. Tolkien in his fantasy The Hobbit unwittingly devised an exquisite description of a globular cluster when he described the fabulous jewel called the “Arkenstone of Thrain”: “It was as if a globe had been filled with moonlight and hung before them in a net woven of the glint of frosty stars…”
There was a 10-year-old boy next to us, Cameron, who knew the sky better than we did. He was pointing out objects using his own telescope, then we would find them in ours. His enthusiasm was contagious and infecting everyone there. He was a kid who knew exactly where he was ... namely on the third planet of a star off on the outskirts of the great Milky Way galaxy.
The entire Sagittarius region shimmers with the milky light of a million million stars. Our sun is but one of several hundred billion stars in the great spiral galaxy that is our home.
The sun’s place in the Galaxy is about two-thirds of the way out from the center of the spiral. The galaxy has a diameter of 100,000 light years. We reside 30,000 light years from the nucleus. As we look toward the bright star clouds near the spout of Sagittarius' teapot, we are looking directly toward the nucleus, the center, of our home galaxy. The Great Sagittarius Star Cloud is our brief tantalizing hint of the star-filled hub of the spiral. Nowhere else in the sky is the prospect more glorious.
But the actual center of the Galaxy is best observed with radio telescopes rather than optical ones. So dense are the clouds of dust and gas in the plane of the Galaxy that our view of the central regions is almost totally obscured. Radio telescopes have revealed a powerful source of radio energy at the very heart of the Galaxy. The source appears to be smaller even than our solar system. Some astronomers suspect the existence of a massive black hole.
So that evening under the stars for us was a brief excursion into the great mystery of the universe. It was particularly delightful to get to know a seventh grader who knew the neighborhood so well.
