Let me start out this column by asking you a question. Everyone knows the sun is the brightest star in the sky. My question is what is the second brightest star in our Butler sky?

Did you say the North Star Polaris? If that's what you said, don't feel too bad because you're only off by just over 40. There are at least that many other stars in the night sky brighter than Polaris.

By the way, the correct answer is Sirius, the bright shiner at the nose of the winter constellation Canis Major the Big Dog.

As a review to locate Polaris in the sky this time of year, look for the Big Dipper high in the Northern sky. If you're facing north, it'll appear nearly upside down. Draw a line in your mind's eye between the stars Merak and Dubhe on the side of the pot opposite the Big Dipper's handle. Continue that imaginary line downward, and you'll run right into Polaris. If you make a fist and extend it at arm's length, the distance between Dubhe and Polaris is about three fist widths. Try it. It really works!

So while Polaris might receive some undeserved hoopla about its brightness in the sky, the North Star is a very significant star as far as we're concerned on Earth.

If you're a regular reader, which, by the way, I really appreciate, you know I like to call it the "lynchpin of the heavens" because of my name, but more importantly, every celestial object in the sky, even the moon and the sun, circle Polaris every 24 hours. Polaris is in a fixed position 24/7, anchored about halfway from the northern horizon to the overhead zenith. That's because the North Star shines almost directly across Earth's terrestrial North Pole. As we dwell on this planet, we certainly can't feel its rotation, so the only real physical evidence we have that our world is rotating is watching the reflection of it in the celestial dome as it rotates around Polaris every 24 hours.

As I told you about a couple weeks ago, constellations really close to the North Star like the Big and Little Bear, Cassiopeia the Queen, and Cepheus the King always stay above the horizon as they parade around Polaris. We call these circumpolar stars. If you were to travel farther and farther to the north in Canada, the North Star would be higher in the northern sky and you would have more circumpolar stars. If you traveled into the southern part of the United States and into Mexico, Polaris would be fixed lower in the northern sky and you'd have less circumpolar stars.

All the other stars we see in our night sky that are not close enough to Polaris and aren't circumpolar are referred to as diurnal stars. They, too, are circling around the North Star every 24 hours, but their circles are a lot larger, so much so that the northern portion of their loop is below our northern horizon. So strictly from our visual perspective, these stars rise at some point above the eastern horizon and set in the west, just like the sun and moon.So by no means is the night sky static as it's always on the move. Don't like what you see in the heavens for stars? Just wait, and you'll see new shiners rising in the east. You can easily observe these changes within a couple hours. The star show is always changing!And if the hourly westward dance isn't enough for you, there's also a much slower dance of the stars that takes place from night to night. The Earth's orbit around the sun is to thank for this slow dance. Every 24 hours, every star in the sky shifts slightly to the west by one degree or the width of two full moon lengths. This is because as the Earth circles our sun, our view into space is slowly but constantly being directed toward different direction in space.One way you can prove this to yourself is to find a place with low horizon and walk around to a point where you can line up a fairly bright star that's low in the sky directly above a prominent land structure, like a church steeple or a flagpole. Mark — or at least remember — where you're standing, and also make a mental note of the precise time, at least down to the minute. Go out the next clear night and stand at the same spot at the same time, and you should easily see the star has shifted at least a tiny bit to the west.So not only do the stars shift to the west hour by hour, but also a tiny bit to the west from night to night. Over time, you'll see that if you observe the celestial dome at the same time in the evening — for even just a few weeks — you'll really see the seasonal shift.Over time, constellations in the western sky will sink off the celestial stage, and new constellations will be on the rise every night, rising about four minutes earlier each evening. That's why we have different constellations in different seasons, but just like professional sports, you can have more than one set of seasonal constellations in the sky at a time. For instance, right now we still have a few winter constellations like Gemini the Twins and Auriga the Chariot Driver in the low western sky. In the low eastern sky, summer constellations like Cygnus the Swan and Lyra the Harp are on the rise. In between, we're enjoying Spring star patterns like Leo the Lion. The stars are always on the move, but truthfully, it's Earth that doesn't know how to stand still.One more thing about the North Star.It should really be called "North Stars" because Polaris, like most of the stars you see at glance, is actually a multiple star system of three stars. There's the large part of triplet that you see with the naked eye, but there are two other much smaller stars that you need a high powered telescope to detect. All three stars orbit each other almost 2,500 trillion mikes away!Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, "Pennsylvania Starwatch," available at bookstores and at his website www.lynchandthestars.com.