Twinkle, twinkle little star, how I wonder what you are.

First off, stars are anything but little. Those little lights adorning the night are all big balls of gas, some much bigger than others.

Even the smallest shiners we gaze upon are much bigger than our home planet. Stars are basically huge balls of mainly hydrogen gas with incredible nuclear fusion furnaces deep within, near their cores.

The closest star to Earth is our sun, a little more than 93 million miles away. That's celestial chicken feed, though, compared with the rest of the stars that show themselves after our sun is down.

The next closest star to the Earth is almost 25 trillion miles away. That's a 25 with twelve zeros after it! That works out to be 4.3 light years away, with just one light year equaling 5.8 trillion miles, or the distance that a beam of light travels in one year's time.

Most stars that you see at a glance in the sky are much farther, some of them hundreds, even thousands of light years away.

No matter how far away, all stars are about the same and are similar to our own sun, whether they are in our own Milky Way galaxy or one of the billions of other galaxies in our universe that stretches out to God knows where.

In fact, at least in our home Milky Way, the sun is considered by most astronomers to be of average size and mass. It's 864,000 miles in diameter, compared to our less than 8,000 mile wide Earth. More importantly, the sun is a heck of a lot more massive than our Earth. How does 300,000 times more massive than our world grab you?

I know it's hard to believe that a ball of gas can be that heavy, but it truly is.

Okay, so the sun is a big ball of mainly hydrogen gas. What makes it shine?

Why is the temperature of its surface more than 10,000 degrees F?

As I said before, the sun and the other stars have nuclear fusion furnaces inside of them, but what fuels that furnace?

The answer is simple.

It's gravity! The same force that makes your skin sag as you get older is ultimately fueling the sun and other stars.

Because the mass of the sun is so large, the gravitational field around it is so strong that not only do the planets in our solar system obediently orbit it, the big ball of gas that is our sun is being squeezed by its own gravity.

It's estimated that this gravitational squeezing of our sun increases the pressure inside like crazy, to the tune of more than 500 billion pounds per square inch toward the center.

In turn, that drives up the temperature at the sun's core to an estimated 27 million degrees. That tremendous heat is the trigger for the nuclear fusion furnace.

Nuclear fusion is a tremendously complicated process, but the essence is this:

Hydrogen atoms at the core of the sun are moving very fast because of the tremendous heat, forcing tremendous collisions between them. These collisions are so violent that the hydrogen atoms fuse together, creating heavier helium atoms.

In the process, energy is produced that finds its way to the sun's surface. By the time this radiation reaches the visible surface of the sun, it's cooled off to a little more than 10,000 degrees F.

Now there's a little more to it, but I know the Butler Eagle wants to have other things in its paper today than just this column. The gist of it is that gravity is the trigger; hydrogen is the fuel of the sun, or any other star for that matter; helium is the ash; and energy is the byproduct.

Now what about the twinkling of those not-so-little stars?

Well that has nothing to do with the stars themselves, but rather our turbulent atmosphere jerking around the light waves from these stars that are so far away. The higher the winds are in all levels of the atmosphere, the more the stars will twinkle.

That's why amateur astronomers like to observe with their telescopes on calm, clear evenings. The images through telescopes of any size are cleaner and wind chill doesn't have to be dealt with!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and author of the book, "Pennsylvania Starwatch", available at bookstores and at his Web site www.lynchandthestars.com