'Z' stars easier to spot than to pronounce
Last week in Starwatch I featured the constellation Scorpius the Scorpion.
It’s one of the few constellations that indeed resembles what it’s supposed to be in the Butler night sky. Its brightest star, Antares, marks the heart of the beast.
It’s easy to spot Scorpius. Look in the southern sky just above the horizon for the brightest star you can see. That’s Antares, with a decidedly ruddy hue to it.
To the upper right of Antares, look for three stars evenly spaced in a short diagonal line. That’s the head of Scorpius.
It’s easy to see the tail of Scorpius to the lower left of Antares, although you might have a tough time seeing the stinger, depending on how on high the tree line is.
Just to the right of the three stars that make up Scorpius’ head is the faint constellation Libra the Scales.
Unlike Scorpius, it looks nothing like what it’s supposed to be. It allegedly outlines a set of scales, the semi-universal symbol of justice.
Libra is made up of incredibly faint stars with two exceptions: Zubeneschamali, pronounced zuba-nesh-a-molly, and Zubenelgenubi, pronounced zoo-ben-el-je-new-bee. Try to say those mouthfuls over and over as fast as you can!
Spotting what I call the “Z” stars is much easier than pronouncing them. To the right of the three stars of Scorpius’s head, look for two identical, moderately bright stars. They’ll be oriented diagonally, with Zubeneschamali on the upper left, and Zubenelgenubi on the lower right.
These tough, tongue-twisting names are Arabic, and translate into English as the south claw and north claw.
What do “claw” stars have to do with a Roman scale? Absolutely nothing!
As it turns out, the constellation Libra was invented by the Roman Emperor Julius Caesar around the time of Christ. Originally the Z stars of Libra were the claws of the neighboring constellation Scorpius the Scorpion. One day, Caesar just decided to hack off the claws of Scorpius and make the “Z” stars and few others around them into the new constellation Libra the Scales. Caesar had that kind of power!
As with many stars, Zubenelgenubi appears to the naked eye as a single star, but like many stars is actually a multiple star system. It’s made up of three stars, all revolving around each other, 76 light-years away from Earth.
If you’re new to this column, light-years are the easiest way to describe the incredible distance to the stars. A light-year is defined as the distance a beam of light travels in a year, about 5.8 trillion miles. The three stars of Zubenelgenubi are nearly 440 trillion miles away!
Zubeneschamali is even farther away, at 185 light-years distant. It’s a blue giant star well over four million miles in diameter. Our own sun isn’t even a million miles across. Zubeneschamali’s surface temperature is believed to be over 22,000 degrees Fahrenheit, more than twice as hot as our sun.
Enjoy the two tongue-twisting stars of summer. Don’t feel bad if you can’t pronounce them. I’ve been into stargazing nearly 50 years and still stumble on them!
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and adventurepublications.net. Contact him at mikewlynch@comcast.net.
