Jimmy Westlake: What we don’t see
May 20, 2007
I’ve been an astronomer for so long that it’s hard to remember a time when I looked up at the night sky and was totally lost. I was about 12 years old when I had an epiphany one night while looking up at the stars. Suddenly, the utter randomness of the myriad stars transformed into the familiar shapes and patterns I had studied on my star charts. Ever since then, the sky, for me, has been full of starry friends and I am never alone at night.
On a recent visit to Hawaii, I found myself lost again as I stared at a patch of unfamiliar sky not visible from Colorado. You see, the Earth blocks a large region of the southern sky from our view in Colorado, so there is an alien quadrant of the universe down under just waiting to be discovered. It was like being a kid again, and it took several minutes before the patterns I’ve always seen on my star charts came into focus.
There is one constellation in particular that I wish I could see in its entirety from my Colorado home. It’s Centaurus, the Centaur. He teases and taunts me every spring when he briefly pops his head up above the southern mountains. I always get the feeling that if I could just climb to the top of a tall tree, I could see over that fence of mountains to glimpse the wonders beyond. Of course, there is no tree tall enough to accomplish that!
You can see the Centaur, too, peeking in on us. Go outside around 10 p.m. in late May and look directly below the bright star Spica, high up in the south. There, you’ll see the Centaur’s triangular head, his arms and human torso, but his equine half remains hidden from view.
Here’s what we don’t see, hidden behind the Earth: The front hooves of the Centaur are two of the brightest stars in the whole sky, named Rigel Kentaurus and Hadar. Rigel Kentaurus is perhaps better known by its other name, Alpha Centauri, the closest star system to our own. At a distance of only 4.3 light years, the triple star system of Alpha Centauri brightly beckons us as the Centaur’s foot.
But that’s not all that’s hidden just beyond our view. Tucked in under the belly of the Centaur are the four stars of Crux, the famous Southern Cross. Although it’s the smallest of the 88 constellations, Crux’s reputation has reached legendary status. It sits in one of the most spectacular regions of the southern Milky Way, surrounded by star clouds, clusters and nebulae.
If you can’t travel to Hawaii or the tropics this spring, just use your imagination to fill in the portions of the southern sky that we don’t see.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the Web sites of CNN.com, NASA’s “Astronomy Picture of the Day,” Spaceweather.com, Space.com, Discover.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His “Celestial News” article appears weekly in the local Steamboat Pilot newspaper.