By Jimmy Westlake, professor of physical science, Alpine Campus
“When you see the Southern Cross for the first time/You understand now why you came this way… ”
I think these lyrics from the hit song by Crosby, Stills, and Nash sum up many people’s feelings about seeing the constellation of the Southern Cross for the very first time. Although it is the tiniest of the 88 official constellations, its reputation is larger than most, even though many people living in the Northern Hemisphere have never seen it. Its likeness adorns the flags of both New Zealand and Australia.
The Southern Cross, or Crux as it is now officially named, used to be visible from much of Europe, but no more. It was originally seen by the ancient Greek civilization around 1000 BC and was then considered to represent the hind feet of a giant Centaur pictured in the stars. Over the centuries, however, the slow wobble of the Earth on its axis (called precession) carried the stars of Crux south and out of view of Greece and the rest of Europe, so it was gradually forgotten. European sailors rediscovered these stars during the sixteenth and seventeenth centuries as they began exploring the southern seas. Many of these European explorers were of the Christian faith and were awestruck by the resemblance of these stars to a tiny crucifix in the heavens. Amerigo Vespucci himself claimed to be the first European to ever see these stars during his third voyage in 1501, but the four stars forming the Southern Cross didn’t appear on star charts as separate and distinct from the Centaur constellation until Dutch astronomer Petrus Plancius depicted Crux on his celestial globe in 1589. It officially became the smallest of our 88 constellations in 1920.
Crux is not visible in its entirety from any location north of 27º latitude, which includes most of the United States. April and May are the best months to observe it. I’ve seen the top star of the Southern Cross briefly pop up above the southern horizon from New Orleans and witnessed the entire cross barely clear the ocean waves from Key West, Florida. It wasn’t until I traveled to the Big Island of Hawaii that I could see the Southern Cross standing well above the southern horizon. Eventually, precession will carry Crux back into the view of mid-northern latitudes once again, but that will be centuries in the future. Until then, travel to the tropics is the only way to view the Southern Cross for yourself.
Professor 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 all around the world. His “Celestial News” column appears weekly in the Steamboat Pilot newspaper. His “Cosmic Moment” radio spots can be heard on local radio station KFMU. Also, check out Jimmy’s website at www.jwestlake.com.