Thursday, March 25, 2010

Tripping the Light Fantastic - Part 1

After sunset on winter and early spring nights, you can spot the luminous band of the Winter Milky Way arching across the sky. The cloudlike apparition is the combined light of billions of stars in the spiral arms of our home galaxy. We look at these arms edgewise, from our position within the platter-shaped galaxy.

What we call the Winter Milky Way is the view looking outward, toward the edge of the galaxy. Contrast that with our summertime view of the Milky Way, when we look toward the center of the galaxy.

Let’s trip our way along the Winter Milky Way.

1) About an hour after your local sunset time, face south. If you don’t know the cardinal directions at your location and you don’t have a compass, make note of where the sun sets on the horizon. That spot is approximately west. Stand with your right shoulder to the west, and you’ll be facing approximately south.

Star maps created with Your Sky

2) Moving up from the southern horizon, the first bright star you encounter is Sirius, brightest star in the constellation Canis Major the Big Dog and brightest star in the entire night sky. Extending southward from Sirius is the upside-down-Y asterism (star pattern) of the more prominent stars in Canis Major.

3) Follow the Milky Way up to the next recognizable pattern, the hourglass asterism of the constellation Orion the Hunter. This is a rectangle of stars cinched in the middle by a diagonal line of three evenly-spaced stars: Orion’s Belt.

4) Continuing upward, the Milky Way is next bracketed by Gemini the Twins on the left (east) and Taurus the Bull on the right (west). Gemini is made noticeable by its two brightest stars, Castor and Pollux, the names of the mythological twins. Taurus may be recognized by the V-shaped collection of stars known as the Hyades star cluster, the orange giant star Aldebaran, marking the Bull’s eye, and a spangled cloud above (northwest of) both star cluster and star: the famous Pleiades or Seven Sisters star cluster.

Next week, we’ll trip the light fantastic on the northern end of the Winter Milky Way.

Thursday, March 11, 2010

Delusions of Grandeur

I love that the naked-eye planets have unique colors. It's true that some beginning stargazers have actually accused me of being “delusional” when I’ve attempted to point out to them color differences among various planets and stars. And in the interest of full disclosure, I suppose I should mention that I’m pretty sensitive to the shades and subtleties of color, and am fully prepared to vigorously debate the relative merits of cornflower and periwinkle.

But three of the five naked-eye planets are visible in the night sky now, so you can put my claim to the test yourself.

Star maps created with Your Sky

Right after sunset, about one fist-width above the western horizon, look for the bright beacon of our neighboring planet Venus. (Never look directly at the Sun!) A fist-width is your fist held at arm’s length against the sky and measured across the knuckles. Venus is the third brightest celestial object in Earth’s sky, after the Sun and the Moon, and it blazes with a bluish-white hue.

About a half-hour after sunset, face east-southeast and look for bright planet Mars. It’s shining just below Castor and Pollux, the namesake stars of Gemini the Twins. You can also find it by drawing an imaginary line from Sirius, the brightest star in the sky, to Procyon, the bright star northeast of Sirius (that is, a little above it and to the left). Keep going past Procyon, a little less than the distance between Sirius and Procyon, and look for a reddish or orange-colored "star." It appears distinctively copper to me. This is the Red Planet, and its colorful name refers to the high concentration of iron oxide (aka rust) in the planet’s top layer of rock and dust.

About an hour after sunset, face east and look for a bright luminary coming up over the eastern horizon. It’s not quite as bright as Mars, but brighter than Regulus, the star at the bottom of the Sickle asterism (star pattern). The Sickle marks the head of the constellation Leo the Lion. The bright newcomer is the ringed planet Saturn, and it has a golden-yellow hue. This coloration is caused by sunlight (from our yellow Sun) reflecting off the ammonia clouds in Saturn’s upper atmosphere.

By the way, massive Jupiter and petite Mercury, the other two naked-eye planets, are aligned too close to the Sun right now— from our vantage point on Earth— to be visible. But yes, they too display unique hues.

That’s my story, and I’m sticking to it.

Thursday, March 4, 2010

Deep-Sky Diving

Spring is in the air. I can feel it in my bones. Unfortunately, that’s no longer a figure of speech, but a physical reality, as the arthritis that runs in my family now sends exploratory twinges through my joints whenever the weather changes.

I am, admittedly, something of a fair-weather observer. I rarely break out my telescope during December, January, or February. I don’t like the cold, never have, never will. During the winter months, I’m usually satisfied to do quick sessions of naked-eye stargazing, eliminating the need for long johns, clunky boots, and layering. Reconnecting with the familiar patterns of the winter sky—Orion’s hourglass, Canis Major’s upside-down “Y,” Auriga’s pentagon—and reassuring myself that they’re still there, just where I left them, proves to be as bracing as the cold slap of night air that accompanies our reunion.

It was an evening in March when I began my life as an amateur astronomer, when observing the sky became the context for my life. So March always feels to me like the start of stargazing season. And each time it rolls around, I can’t help but recall my first tentative forays into what I call “deep-sky diving.”

The comparison to scuba diving is no accident. When, as a beginner, I began attending star parties at my astronomy club’s private observatory, there was, on each occasion, a moment when I had to give up the daylight and surrender myself to the dark. I had to psych myself up each time to make that transition—to turn on my red flashlight and begin picking my way around the observing field equipped only with that dim, eerily-colored light. To be, in essence, completely out of my element.

Ironically, this fish-out-of-water feeling reminded me of the scuba diving vacation I took on the island of St. Croix, many moons ago. I had never been scuba diving and hadn’t had a single lesson (not even in a pool), but I had an irresistible desire to go. So I capriciously enrolled in a certification course down there, and off I went.

I was completely unprepared for the physical fear I would experience in letting go of my terrestrial, atmosphere-breathing self in order to immerse myself in a water-world. My first day in the ocean was spent in a series of exercises that each ended with my panicked bolt to the surface, where my exasperated instructor would berate me (as he should have) for doing something that was potentially hazardous to my health.

Then he had a breakthrough, and took me into shallow water (like a pool, perhaps?). He had me do exercises there until I became more comfortable with breathing underwater, moving me gradually into deeper water. Then I had my breakthrough, reaching that pivotal moment when my awe at the undersea world to which I had mysteriously gained access overtook my fear of relying on a regulator and tank for each breath.

By the end of the week, I was confidently doing 60-foot dives in open water and exploring dazzling, brilliantly-hued coral reefs.

And so it was to be a novice sky observer. The unfamiliar star patterns, the totally foreign equipment, the strange lingo, and the breadth of science knowledge those intense people-of-the-dark had—all were terribly intimidating. In that state of nervous excitement, making the transition from light to dark made me gasp for air like a panicky diving student. It wasn’t fear of the dark, but rather fear of the unknown, loss of control, and being out of my comfort zone that squeezed my chest those first few months.

Like breathing underwater, I got used to seeing in the dark. I learned which end of the telescope to look into, how to get the Moon into a telescope, how to identify naked-eye star patterns and find my way around the sky, what a glorious thing a globular cluster is, how to spot the pencil line of the Cassini Division in the rings of Saturn. It helped that I was on a mission, finally fulfilling a life-long interest and deeply-held desire. Pushing through the discomfort each time made me a little less uneasy for the next. Each new skill I acquired, each new term I learned, each new object I observed: each gave me a little bit more confidence and stoked my passion.

The first time I looked through a telescope, I was 43. I didn’t know what a star was, had no idea why the Moon looked the way it did as it went through its phases, couldn’t find the North Star. If you’re younger than 43 and are interested in getting started in hobby astronomy, don’t wait as long as I did. Do it now. The younger your eyes are, the more nuances you’re likely to see in celestial objects and the more years you’ll have to train your eyes to pick out those nuances.

If you’re older than 43, hop to it. Time’s a-wasting. There’s a lot to see out there in your universe. The more you find out, the more you’ll want to know, so you’d better get started. Trust me on this.

Whenever, however, wherever: embrace the dark. Oh, and don’t forget to breathe.