Someone once said to me, “You’ve seen one star, you’ve seen them all.” But nothing could be farther from the truth.
The fact is every star you see in the night sky is unique as people are on Earth.
Every star is different in size and age. More than two-thirds of all stars we see have a companion star or more orbiting them.
And because orbiting NASA spacecraft have discovered more than 3,000 “exoplanets” orbiting some 1,000 nearby stars, kjl astronomers know realize there are many times more unseen planets than stars!
And in this week’s winter night sky, there are eight of the top 20 brightest stars that are easy to find. They are all at least 1st magnitude—a scale of brightness where the lower the number the brighter an object. The faintest a normal person sees from a dark observing site is 6th magnitude. A typical suburban backyard will have 3rd magnitude as the faintest we see, with the Big Dipper and North Star, Polaris, around 2nd magnitude stars.
Indeed, much like snowflakes, no two stars are exactly alike. Visualizing their exact physical properties is a challenge being met by modern astronomy.
Those bright stars of our winter nights are Betelgeuse and Rigel in Orion the Hunter; Sirius in Canis Major; Procyon in Canis Minor; Capella in Auriga the Chariot Driver; Castor and Pollux in Gemini; and Aldebaran in Taurus the Bull.
Let’s first look at the red, left shoulder star of Betelgeuse, pronounced BEATLE-juice, and translated from Arabic meaning “armpit of the giant.” This is a huge star—it would fill up our Solar System to the orbit of Mars! The size fluctuates as does the star’s brightness, from 0.3 to 1.3 magnitude. At first thought to be an old star, Betelgeuse is in fact very young, maybe formed 100 million years ago when dinosaurs roamed the Earth. Distinctly red in color, it is 310 Light Years away. Like a fire, the color of stars gives a clue to the surface temperature. Our white-yellow Sun has a surface temperature of 6,000 F. degrees. The world’s best telescopes have seen cooler splotches on the 4,000 F. degree surface of Betelgeuse.
Orion’s right knee is Rigel is blue-white, with a surface temperature about twice that of Betelgeuse. The light we see from Rigel (RYE-jell) left 910 years ago, yet its energy output is tremendous.
Sirius is the brightest star in the sky at minus -1.5 magnitude. Sirius (SEAR-e-us) is also one of our Sun’s closest neighbors at only 8.71 Light Years away. And its surface is white hot, 10,000 F. degrees. If Sirius traded places with Rigel, you’d need telescope to see Sirius and Rigel would cast a shadow in daylight! In Greek, the name means “sparkling” or “scorching.” This is the “Dog Star” so important to ancient Egypt and called Al Shira.
When seen rising in the morning sky before the Sun (in April), the Nile River would flood soon, bringing fertility again. This star is also the culprit of the “Dog Days of Summer.” Sirius is high in the summer daytime skies of June and July, and the ancient peoples imagined the brightest of stars contributing heat to the Earth’s already hot summers. Sirius has a companion star, a white dwarf, that is just barely visible to the keenest observer with a high-quality backyard telescope.
Procyon (PRO-see-on), high above Sirius and to the left of Orion, is also in the Sun’s neighborhood, only 11.3 Light Years away. That means that at a speed of 186,000 miles per second, light that left Procyon in 2008 is just reaching Earth, and therefore, your eyes. A Light Year is about 6 trillion miles, so this yellow-white star is more than 66 trillion miles away—extremely close as outer space distances go.
Capella at magnitude 0.08 and 42 Light Years away, is the sixth brightest star in all the sky, yet one of the most ignored of the Top 20 1st magnitude stars. Maybe it’s because its constellation, Auriga the Charioteer in the north, is such an ancient concept. Who names their kid “Auriga” (aw-REYE-ga)? And as for a chariot driver…who alive has ever met one? But Capella (KA-pell-a) is beautiful yellow almost like gold, and it has a small companion star orbiting it. Capella translates into “she goat,” apparently what the chariot driver is carrying around.
Castor, the top star of the brothers Gemini, is an astonishing system of six stars! The naked eye sees a blue-white star of 1.6 magnitude. With a department store telescope, Castor’s (KAS-tor) two close stars are revealed. And they orbit each other while orbiting Castor! The other stars of this amazing system, 45 Light Years away, are seen with more professional equipment.
Pollux (PALL-ux) is an orange giant that is a close 36 Light Years away. This star puts out more than 30 times the energy of our Sun and has at least one planet orbiting it—some 3 times the size of our Jupiter! This star puts out more than 30 times the energy of our Sun and has at least one planet orbiting it—some 3 times the size of our Jupiter!
Members of the ancient stories of the Argonauts’ crew, Castor and Pollux were half-brothers sharing the same mother. Greek mythology says Castor’s father is King Tyndareus of Sparta, while the father of Pollux was the god Zeus.
Aldebaran, our last stellar stop, is the red eye of the bull, Taurus. The horns of the bull taper away from this fat and rosy red star. Translated in Arabic as the “flower,” as in following The Pleiades—the seven stars in the bull’s shoulder. Bloated like Betelgeuse in the sky below it, Aldebaran would also engulf at least Earth in our solar orbit if placed in the center of our Sun’s system. Sixty-eight Light Years away, this red giant is probably an old star and might explode in the next billion years.
Look up at the winter stars with a fresh pair of eyes and see each stellar point as a special place in our incredible Universe. And learn a few starry names by checking into a myriad of resources from our information highway that seems as endless as the starry night.