Animal-rights activists in ancient Greece immortalized bears with both a little and big version — both are at their highest in spring skies. You can trace the bear’s shape in Ursa Major’s stars if you have a few shots of vodka first. Otherwise, it looks like a dipper or a plow.
It’s a mystery how disparate cultures like the American Indians, Germanic tribes, and ancient Greeks all saw a bear in these same stars. How could civilizations that never met visualize identical hallucinogenic shapes? They accomplished something truly historical: spreading misinformation before there was an Internet.
Each night this month, the Big Dipper appears higher at 10 o’clock until it reaches maximum altitude during April’s final week. The pointer stars at the bowl’s left then aim straight down to the North Star. This verticality is striking — one of the night’s milestone moments. The topmost star, Merak, has a nice alien ring that sounds like a surname on Krypton. Below it, Dubhe (say Dubby, not Dubya) is a different story, because listeners chuckle, “C’mon, there’s no star named Dubby.”
What about the well-known concept of using the Big Dipper’s whirling around the North Star as a clock, to tell time? Although a few books advocate this, it’s idiotic. The Dipper goes around Polaris the wrong way, counterclockwise. So, it could serve as a 24-hour clock only if you could get behind those stars in another dimension, and look this way.
Like any broken clock, it gives the true time occasionally. Once a year, the “hour hand” (a line from Polaris to the pointer stars) correctly points straight up at midnight. When this happens depends on where you live in your time zone — it’s generally between March 2 and 12.
Do you remember the first time you noticed the double star near the end of the Dipper’s handle, composed of bright Mizar and little Alcor? “Al” means “the” in Arabic, so Al-stars fill the sky, as in Altair and Aldebaran. Alcor cryptically means “the abandoned one.”
The ancient Arabs regarded spotting Alcor as a successful test of keen vision. These days, it’s more like a feel-good exercise for nerds with terrible eyesight. Anyone can see it, even from light-polluted cities, so maybe the star has brightened throughout the centuries.
The sky’s most famous bright double star also is the only one that never sets. You have to venture south of North Carolina to ever see it vanish. Safe bet: No one’s ever gone to Dixie for that purpose.
Another oddity is that ancient Arabs called this double star the “horse and rider.” But this is supposed to be a bear. Why drag the Kentucky Derby into the picture? Because the constellation wasn’t a bear originally. The Sumerians and Babylonians called it a chariot. That definitely works better in this Rorschach spot than “Smokey the Bear.” But before we give the Babs too much credit, remember: They originally called Orion a sheep.
Back to science. All Dipper stars except the two at the ends lie at the same 80-light-year distance from us. They share the same spectral type (A), nearly the same brightness, and the same motion through space. In other words: This is a star cluster. It’s big because it’s the nearest cluster to Earth.
Discovered in 1869, the Ursa Major moving group hovers so close that members and former members — perhaps even Sirius — lie all around us in the sky.
Because this entire region floats above the Milky Way’s plane, only a smattering of stars lies between us and the emptiness of intergalactic space. That’s why the famous Hubble Deep Field photo was taken in Ursa Major. No obscuring dust. Through this window, we can see countless galaxies beyond our own, including the bright pair M81 and M82 10 million light-years away. Both are found easily in binoculars by extending and doubling the diagonal line from Phecda (the highest bowl star) through Dubhe.
Not one 1st-magnitude star graces this whole lonely part of the sky. Yet, this most famous pattern in the heavens gave many of us our start long ago. These days, the “Ursa” component still gives me a start.
