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Perfect Stellar Geometry!


The Butler night sky is such a collection of wonderful pictures, patterns,and great stories.

Ancient cultures used individual constellations as visual aids to spin tales of mythology and legends from generation to generation.

Most of the best-known adventures in this part of the world are spinoffs of Greek and Roman mythology, and they're great soap operas in the skies.

The common thread of most constellations is that they don't look much like what they're supposed to be. You really have to put your imagination into overdrive. That's OK in my book because it's part of what makes stargazing so much fun.

Many constellations display pretty unique geometrical shapes and patterns called asterisms. The connecting lines of stars in the constellation Cassiopeia the Queen resembles a giant W in the heavens.

The right side of Leo the Lion is made up of a backward question mark. The constellation Auriga, the Chariot Driver, looks like a lopsided pentagon.

One of the best asterisms is the seven stars that form the rear end and tail of Ursa Major, the Big Bear. You see that every clear night as the Big Dipper.

Much larger asterisms in the sky use stars from several adjoining constellations. One asterism is the Summer Triangle, made up of the

brightest stars from three constellations. The stars at the corners of the triangle are Vega, the brightest star in the constellation Lyra the Harp; Deneb in the constellation Cygnus the Swan; and Altair in Aquila the Eagle.

Each one of these stars is the brightest shiner in its home constellation.

The Summer Triangle is easy to see in both the summer and autumn sky and can lead you to other constellations in the vicinity.

Asterisms are great tools for learning your way around the heavens.

Even better is the Winter Triangle, now on full display in the early evening southern sky. It's a perfect equilateral triangle of three bright stars from three separate constellations.

As you can see in the diagram, it's made up of Betelgeuse from the constellation Orion the Hunter; Procyon, the brightest star in the small constellation Canis Minor the Little Dog; and Sirius, the brightest star in Canis Major the Big Dog.

Unless you're viewing from a lit-up shopping mall parking lot, you should have no trouble spotting the perfect Winter Triangle. It's so bright! In fact, Sirius, at the bottom of the triad, is the brightest star available in the night sky.

Sirius and Procyon are almost twice the diameter of our sun and are much more luminous than our home star, but the main reason they're so bright is that they're relatively close to the Earth.

Procyon is eleven light-years away, and Sirius is just over eight light-years away. Just one light-year is nearly six trillion miles. Believe it or not, that's considered down the block astronomically. If you could fly to Sirius in a jet airliner averaging 500 miles per hour, it would take you more than 11 million years to get there!


Sirius can be a whole lot of fun to view through even a small telescope. That's because it never gets very high in the sky, and its light has to travel through more of Earth's blurring atmosphere to reach our eyes. If upper atmosphere winds are strong and there's a lot of turbulence, Sirius can appear as a changing kaleidoscope of colors as its light rays bounce around.

The third star of the winter triangle, Betelgeuse, is a huge star around 500 light-years away. It's a super red giant star nearly a billion miles in diameter, and sooner or later, it will burst in a colossal supernova explosion, maybe within the next million years. I wouldn't wait up for it, though. Until then, Betelgeuse will be a proud member of the Winter Triangle, shining brightly with its easily seen reddish hue.

The perfect Winter Triangle. Is it just a coincidence? Or not?

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 Contact him at

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