What you see in our Butler night sky is not always reality. There are many illusions up there.

Whenever you gaze upon the starry sky you're not seeing the stars in real time. You're actually gazing into the past in varying degrees.

Everyone knows the stars we see at night are way far away. Trying to express their distances in miles involves using values in the trillions, and except for the national debt, most of us don't use trillions all that much.

It's hard to get your mind wrapped around the concept of a trillion of anything. We're talking a thousand billion here!

It's easier to express stellar distance in light-years. A light-year is the distance a beam of light travels in one year's time, moving at the speed of light which is just more than 186,000 miles a second. If you do the calculations that works out to about six trillion miles for just one light-year.

On average most stars you see in the heavens with just your naked eye are about 100 light-years, or 600 trillion miles away!

A good example of a star that's 100 light-years away is Alkaid, the star at the end of the handle of the Big Dipper. Since light travels at a set speed, when you see Alkaid you're not seeing it as it is right now but as it was in 1904, when less than 15 percent of American homes had bathtubs!

Many other naked eye stars in the sky are a lot farther out than Alkaid. Some stars are thousands of light years away!

One such star is Deneb, the brightest star marking the tail of the constellation Cygnus the Swan, flying high over the evening southwestern sky this time of year. Deneb is about 1,500 light-years away, so we're seeing Deneb as it was around the year 500, long before there even was America!

As far away as Deneb is, there are many other stars even farther away, many of which can be seen with the naked eye.

The question I get asked a lot is whether some of the stars you see in the night sky may be, at this present moment, not around anymore. Are we just seeing light from a star that's met its maker? Have they already blown up in a colossal supernova explosion, as in the case of super massive stars, or have they shrunk into white dwarfs like our sun?

Rest assured that every individual star you can see with your eyes or with a small telescope is still alive and kicking. The lifetime of a fully functioning star is at the very minimum two billion years and there's no way, no matter how many carrots you eat, that you'll see a star with your naked eye that is two billion light years away. All those shiners in the celestial dome are still there.Another major illusion in the sky is that the stars that you see are single stars sitting out there by themselves.Most of them are actually star systems. Some are binary stars, where two stars are revolving around each other. Some may be triple, quadruplet, quintuplet or even more multiple star systems, with all of the member stars orbiting around each other in sometimes very complicated cosmic dances. Our sun, sitting out in this part of the galaxy all by itself, is the exception rather than the rule.There's also double stars in the sky that aren't members of the same stellar family, but rather stars that just happen to be in the same line of sight from Earth. They're called optical doubles, and a great example of that is in the handle of the Big Dipper.The middle star of the handle that you see right away is Mizar, but if you look just above and slightly to the left of Mizar you'll see a dimmer star called Alcor. Mizar is about 78 light years away and Alcor is a little over 81 light years away. Physically they have nothing to do with each other.Another great double star, probably the prettiest in the sky, is Albireo. It<B><I> </B></I>marks the head of Cygnus the Swan, also known as the foot of the famous “Northern Cross.”With the naked eye it looks like an unassuming single star, but with even a small telescope you can see two stars, one with a distinct bluish hue and the other sporting an orange glow. They're a gorgeous duo of stars. They lie about 380 light years from our backyards. It's not known if they're actually orbiting each other in a binary system, but if they are their orbit around each other would take about 100,000 years. Don't wait up for that. You need your beauty sleep!Celestial Encounter this Week: If you're a very early riser try to catch the Leonid Meteor Showers, one of the better meteor showers of the year. It peaks out early in the morning this Wednesday. The best time to look is from about 2 a.m. to morning twilight. Dress warm and bring blankets. Lie back in a lawn chair, preferably in a reclining lawn chair, and roll your eyes all around the sky, slightly favoring the eastern half. It's called the Leonids because meteors seem to trail back in the direction of the constellation Leo the Lion, which resembles a backward question mark rising diagonally in the eastern heavens.Also, keep enjoying the bright planet Jupiter, still the brightest starlike object in the sky. Even with a small telescope you can see up to four of its larger “Galilean” moons and maybe some of its horizontal cloud bands.On Monday night the waxing gibbous moon will be just to the upper left of Jupiter in a celestial hug, and on Tuesday night the approaching full moon will be just to the upper right of the largest planet of our solar system.Don't miss the moon and Jupiter early this week. You'll love it!<B><I>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 his website www.lynchandthestars.com and at bookstores.</I></B>