As our home planet orbits the sun throughout the year, it regularly plows through debris trails left behind by comets and even asteroids. When that happens, we have a meteor shower.

There's about a half dozen decent meteor showers a year, with the best ones being the Perseids around Aug. 11 to 12 and the Geminids Dec. 13 to 14. The Leonid meteor shower, which peaks this week, is arguably the third or fourth best of the year, but this year, it could be extra special.

That's because the debris trail left behind by comets and asteroids can vary in density from year to year. The individual bits of dust and debris, usually no more than pebble size, can travel in denser clumps along the trail, especially in the case of comets.

Comets are basically dirty snowballs embedded with debris. Most comets travel in highly elongated orbits that take them from near the sun to well past the outer planets in our solar system. When they pass close by our sun, they partially melt. Some of the really small comets break up completely, but the ones that are large enough to fuel meteor showers can survive multiple passes by our home star.

The parent comet for the Leonid meteor shower is Comet Tempel-Tuttle, which orbits the sun every 33 years. Tempel-Tuttle's last pass by the sun and Earth was in February 1998.

At that time, a large clump of debris was melted off the comet, and from 1998 to 2001 the Leonids were fantastic showers. I remember seeing more than 150 meteors an hour in 1998. There was a lot of fresh ammunition!

That clump has been partially diminished and has moved on. The next time Tempel-Tuttle comes in 2031, it will produce another huge clump of debris, and during the two or three years following that passage, the Leonid meteor shower should be really, really great once again.

While we won't have the meteor "storms" we had around the turn of this century, the Leonids still might put on quite a show this week because the earth will be moving through a fairly dense clump of debris left behind by Comet Tempel-Tuttle in 1466. No one knows for sure, but that might produce a meteor shower with more than 100 meteors an hour.

The best show will be above Asia, but it's certainly worth a look-see around here. The Leonids will be around most of this week, but the peak will be early Tuesday morning from around 2 a.m. to morning twilight. Morning hours are always best for meteor watching because we're on the side of our rotating Earth that's passing right into the debris trail. On Tuesday morning, the Earth will be in the thickest part.

Another factor in our favor this year for the Leonids is that we'll have no moonlight in the sky causing interference.

The best thing to do is set the alarm for a very early wake-up call Tuesday morning, say around 1 a.m. or so, and head out as far away as you can from city lights. Take blankets and reclining lawn chairs so you can really catch the "falling stars" in style.

This meteor shower is called the Leonids since the meteors all seem to radiate away from the direction of the constellation Leo the Lion, which will be rising in the eastern sky. Don't restrict your viewing to just the east either, but rather roll your eyes all around the skies. You'll know it's a Leonid meteor if its trail points back in the general direction of the constellation Leo.

Meteor shower watching can be a lot of fun with a group because the more eyes you have directed toward the heavens the more meteors you'll see. It's easy to miss them if you're on your own because they'll be all over the sky.

Some of these meteors can hit our atmosphere at speeds of more than 40 miles per second, and air friction quickly incinerates them. Most of the light you see from meteors is not from combustion but rather the chemical reactions with our atmosphere as these bits of debris plow though. The individual columns of air they're coming through temporarily destabilise. Electrons are temporarily knocked away from the nuclei of atoms and molecules, and when that happens, light is given off. Even after a meteor has streaked by, you can sometimes see the lingering trail as atoms and molecules in the column of air are getting their act back together.

I know it's a bit of a leap of faith to get out early and see the Leonid meteor shower Tuesday morning. Again, no one knows exactly how good it's going to be. But personally, I'd go for it. Good meteor showers are well worth the loss of sleep!

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 Web site www.lynchandthestars.com.