Shapes lead us to many constellations

It’s hard to believe, but this is my last Starwatch column for 2014. I hope you had a great Christmas!

This week, I want to point out the big polygons you can see in the early evening Butler sky this time of year.

So what are polygons? Well, if you remember your high school geometry classes, polygons are two-dimensional, multi-sided shapes with straight sides. A three-sided polygon is considered a triangle. A four-sided polygon is a rectangle. A five-sided is a pentagon, and so on.

As soon as it’s dark enough in the early evening we have an easily found triangle, rectangle and pentagon made up by bright stars. In your mind’s eye though, you have to come up with the lines between the stars, but that will be easy.

So why am I doing this? I want you to have quick success finding your way around a good share of the night sky with as little hassle as possible.

Getting to know the constellations is ultimately the best way to navigate in the starry skies, although polygons are actually one of the tools that will help you get to know the constellations. That’s because polygons can be made up of bright stars from multiple constellations, part of a single constellation or even make up an entire constellation.

All three of these kinds are available early this evening. These polygons are also known in stargazing circles as asterisms.

The first polygon is in the very early evening western sky, and it’s a triangle, namely the Summer Triangle. Believe it or not, the last of the summer constellations that were nearly overhead in warmer times are now shining in the western skies.

About a month from now, as the Earth continues in its orbit around the sun, we won’t be facing that part of space where those summer stars are hanging out, so this is your last real chance to see them in the evening for quite a while.

Just look in the low to moderately high western sky for the three brightest stars you can see and that’s it. The brightest of them is Vega, on the lower right hand corner. It is the brightest star in the small and faint constellation Lyra the Harp.

On the lower left is Altair, the brightest shiner marking the heart of Aquila the Eagle.

The highest member of the Summer Triangle is Deneb, the brightest star in the constellation Cygnus the Swan. If you caught my column last week you’ll know that Deneb is also at the top of the “Northern Cross” that lies within Cygnus.

We’re going to move up to a four-sided polygon now, a rectangle, and you’re going to have to move your eyes higher up in the western sky to see it. It’s not all that far from the overhead zenith.

If you’re facing west, look for the four brightest stars you can see that form a diamond, a diagonally orientated rectangle. It’s almost a perfect square. In fact, it’s called the Square of Pegasus that’s supposed to outline the torso of a giant flying horse. Go figure.

Not far away from the Square of Pegasus is the Andromeda Galaxy, the next door neighbor of our Milky Way galaxy.

Even in the city lights it will appear as a fuzzy white blotch in a small telescope or even a good pair of binoculars. In the darker skies of the countryside, especially on a moonless evening, it’s possible to see it with the naked eye as a faint ghostly cloud.

That ghostly cloud is the Andromeda Galaxy, more than two million light years away, with just one light-year equaling nearly six trillion miles!

Over in the moderately high eastern sky, a little to the upper left of the famous constellation Orion, is a fairly easy to see lopsided pentagon made up of five stars. It’s more or less the entirety of the constellation Auriga.

Believe it or not, that pentagon is supposed to outline a retired chariot driver now working as a goat farmer. I’d like to party with the people that came up with that star picture.

By far the brightest star of the pentagon is on the upper left corner. It’s called Capella and marks the spot in the constellation where a mama goat is sitting on the shoulder of the former chariot driver. The bubbly must have really been flowing at that party when the ancients came up with that. Maybe it was a wild new year’s bash.

For extra credit, see if you can spot a tiny three-sided polygon of faint stars, better known as a triangle, to the right of the bright star Capella. That triangle marks the baby goat sitting in the crook of the elbow of the retired chariot driver. They’re cute little stars.

Good luck in your pursuit of the polygons. I hope you find it a lot of fun.

Happy New Year! May 2015 be truly celestial!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and is author of the book “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications and available at bookstores and online at www.adventurepublications.net.