StarWatch: Moravian College Astronomy
MARCH STAR MAP |
- 236 MARCH 4, 2001:
- In the Southern Hemisphere the world is definitely turned upside-down, but it is not as freaky as I imagined it would be. This was my first night in Australia at Siding Spring, this nation’s national observatory, a long seven hour drive northwest of Sydney. I expected to be completely overwhelmed and confused like an adventurer looking out upon a new land for the first time. But I soon discovered that with a little "reverse thinking," and an occasional dip of the head, the heavens became familiar. I kept reminding myself that to an Australian the sky was just perfect the way it appeared. Many of my favorite winter and early spring constellations, such as Orion, Canis Major, Gemini, Leo, and Corvus were there in the north. Unfortunately, so was the bright waning gibbous moon. What struck me as being particularly funny was that the moon appeared through my binoculars exactly the way it looked in my atlas. Many publishers print a reversed and inverted moon in books to correspond to a standard northern hemispheric telescope image. In Australia that is the way the moon looks to the unaided eye. Turning south presented much more of a challenge because here was the portion of the sky which was never seen from the North. The star patterns were conceived by European explorers and scientists making their first venture into the southern hemisphere. Somehow the magic of constellations with names such as Octans, the Octant, and Norma, the Level leaves too much for the imagination to handle. But the Southern Hemisphere does have incredible wonders which make the northern heavens pale in comparison. I’ll talk more about this next week or read ahead at the web address below.
- 237 MARCH 11, 2001:
- The sun retreats, and a humid calm settles over the dome-capped buildings at Siding Spring. The shutter of the four meter begins to ratchet open, clanging and creaking as a sliver of sky is exposed to Australia’s greatest telescope. Venus and Jupiter glint against a sky that is still distinctively blue. My friends, John and Tracy, and I gather our gear and head out. I’m doing something easy tonight, tripoded photography, and simply trying to establish a new reality against a foreign landscape and skyscape. Strange Jurassic sounds permeate the woods surrounding us, then something small runs past Tracy. The wind muffles our whispers. The night always has an element of suspense at a new location, and this is no exception. But the sky is what cements my feet to the ground. It forces me to stay and understand that what I have been marveling at for 40 years, up North has been merely a pale reflection of its true majesty. The eye-catcher is still the Southern Cross and Alpha and Beta Centuri, but the stretch of Milky Way above the Cross has got to be the best piece of celestial real estate which the heavens have to offer. Through binoculars the true meaning of star clouds becomes apparent--sheets of stars billowing out like thunderheads--tens of thousands of tiny pinpoints registered on the canvas of my eyes. Then probably the most startling revelation of the evening is made. I look down, and I can read the words on my white T-shirt. Where is this light coming from? I lift my hands and a diffuse shadow obscures the letters. Tears well within me; my back feels prickly--the Milky Way answers in brilliant silence. Later after moonrise, we return to our cottage. Kangaroos graze in our backyard. Australia is all so new and wonderful.
- 238 MARCH 18, 2001:
Southern Milky Way
- The Milky Way is the galaxy in which we live. It is composed of approximately 400 billion stars, but its unseen mass reserves are equivalent to five times that amount. In short, the Milky Way is king of our local group of galaxies which now number about 35. But try seeing our galaxy during late winter from our locale. It is nearly impossible because we are looking away from its brighter center. And then again, there is that ever pervasive problem of light pollution that plagues even the darkest corners of the Lehigh Valley. I was literally "blown away" by our galaxy’s performance in the bush of Australia. Two hundred twenty-five miles northwest of Sydney at Siding Spring, Australia’s national observatory, the winter Milky Way was an easily seen broad sweep of softly glowing sky. The Milky Way bisected Gemini and passed across Betelgeuse, the red shoulder star of Orion, and it was framed by Sirius and Procyon. Right now Sirius, the brightest star of the night, is visible low in the SSW about 8:30 p.m., and Procyon is again as high above Sirius. Imagine the path of our galaxy extending distinctly between these two stars and you have an idea of its breadth. From "Oz" that was only the beginning. Below Sirius and moving southward, the galaxy narrowed but brightened into an explosion of clusters and nebulae, centered around Crux, the Southern Cross. When our galactic center rose, carrying with it Scorpius and Sagittarius, the Milky Way bowed outward like two plates attached by their edges. One astronomer at Siding Spring couldn’t fathom why it took astronomers so long to realize that our solar system was not in the Milky Way’s center. "All you had to do was go out and look," he quipped. He was right!
- 239 MARCH 25, 2001:
- From the Southern Hemisphere the two satellite galaxies of the Milky Way become visible. They are called the Large and Small Magellanic Clouds. Like wispy barges made from our galaxy "stuff" that have set sail across the cosmos, they appear like smudges against the black sky. Although these galaxies are separated from the Milky Way, they are nevertheless interacting with it. Strands of hydrogen gas have been discovered connecting the Milky Way and them. They were unknown or at least unrecorded until late 1519, when the crew of Ferdinand Magellan approached the straits that now bear his name, and noticed these misty, gossamer regions of the sky. They are true galaxies in their own right; the LMC is about 170,000 light years distant, and the SMC is just a little farther away. On my first night of observing at Siding Spring with a bright moon, the LMC was plainly visible, but the SMC was not. Using binoculars at 8-power under a moonless sky, the LMC had a distinct bar-like central structure and a scattering of luminous patches and knots of material visible south of the galaxy. Later, I discovered that astronomers have reclassified the LMC as a small barred spiral, but I did not interpret this from my observations. Knots of glowing gases, including the huge Tarantula nebula, and lots of new, hot blue stars are additional evidence of the gravitational tugs which are occurring between the LMC, SMC, and the Milky Way. The Tarantula is about 1000 light years across. If moved to the distance of the Orion nebula, the Tarantula would extend 40 lunar diameters across the sky. View the SMC and LMC by going to the Southern Hemisphere astrophoto section of the web page listed below.