HITTING STREAKS.

Byline: Greg Bolt The Register-Guard

Like glittering bugs on the cosmic windshield, bits of might-have-been stars will streak across the sky this weekend as they shoot from frozen space and smash into Earth's warm cushion of air.

The Perseid meteor shower puts on its annual show this weekend as the home planet plows face-first into the primordial debris left by comet Swift-Tuttle.

Depending on where you are and when you look, you could see as few as 20 or as many as 100 meteoroids per hour flash across the sky early Friday and into the weekend.

One of the best things about meteor showers in general, and this one in particular, is that you don't have to know anything about astronomy, much less have some fancy, computer-controlled optics, to see and appreciate the show. All you have to do is open your eyes.

"This is definitely a naked-eye event," said Rick Kang, the Eugene-based outreach coordinator for the University of Oregon's Pine Mountain Observatory east of Bend. "Just relax in a lawn chair and look up."

The only catch is that you have to get up pretty early - or stay up pretty late - to catch the show. The best viewing times will be from just after midnight until just before dawn.

But the chronological real estate around 2 a.m. is shaping up as the choice spot because that's when some people predict the Earth will pass through another, fainter trail left by the comet when it swung through in 1479.

A couple of other things seem to be coming together to make this year's show particularly good. One is that the weather is expected to be reasonably nice with few clouds, and the other is that the moon still will be in its first quarter and will set about 11:30 p.m.

That means clear, dark skies, which is just what you want.

But you'll want to leave the lights of the city behind to get the good skies; look for a place that's clear all the way down to the horizon, such as a hilltop or the high desert, for maximum view.

Meteor showers are what happens when the Earth passes through the trail of debris left by comets, which are balls of ice and dirt made from the leftovers of planet formation.

They circle the sun in oblong orbits that carry them well beyond Pluto before plunging back toward our central star.

Swift-Tuttle last passed through the inner solar system in 1992, quite recently in an orbit that takes 130 years to complete. That presumably recharged the supply of debris that Earth already is passing through.

Most of what you see as shooting stars are the size of sand grains or smaller, although occasionally a larger bit will make a particularly bright streak across the sky.

They burn so brightly not only because they hit the atmosphere at 132,000 miles per hour and heat up from friction, but also because that heat ionizes the air around them and adds to the glow.

The timing of the show is based on the physics of planetary movement. It peaks when the Earth is facing outward into space with the sun behind it.

"As the Earth is rotating, midnight is when we're opposite the sun," Kang said. "The analogy is like bugs hitting a windshield.

`So at predawn, we are the windshield of the Earth, and early in the evening we are the back window of the Earth."

The shower is called the Perseids because if you were to follow the streaks of light back along their path, they would seem to emanate from the constellation Perseus in the northeast sky.

But that's just an optical illusion, similar to the way snowflakes seem to all be coming from the same spot when you drive into a snowstorm.

In fact, meteor streaks can appear anywhere in the sky, and often the ones with the most spectacular trails occur far from the constellation they are named for.

And if you can't watch early Friday, that doesn't mean you've missed the show because the debris is so spread out that the frequency of shooting stars will be affected for several days.

"Any time, even a couple days either side of (Friday), at night there will still be an unusually large amount of meteors," Kang said.

Pine Mountain will not be open when the shower hits its peak early Friday, and the gate leading to the parking lot will be locked.

But the observatory will be open as usual Friday and Saturday evenings and offers a good sky for viewing.

FIRE IN THE SKY

Tips for viewing the Perseid meteor shower this weekend

When: The shower hits its peak early Friday, but meteoroids will be more frequent than usual for several nights before and after. After midnight until about 4 a.m. is the best time to view the meteoroids.

Where to look: Generally toward the northeast, in the direction of the constellation Perseus in the early morning, but scan the entire sky. Find a spot with dark skies and unobstructed horizons.

Viewing: Try watching from a reclining lawn chair, scanning the sky with bare eyes. Don't use binoculars or a telescope.

What you're seeing: The Perseids are cosmic dust left behind by the comet Swift-Tuttle, which last passed through the inner solar system in 1992. The particles hit the atmosphere at up to 40 miles per second, burning up and also ionizing the air molecules around them to add to the show.

On the Web: pmo-sun.uoregon.edu/~pmo/

CAPTION(S):

Perseid meteors, shooting past stars, light the night sky. This long camera exposure creates a circular star pattern that's intersected by the paths of two reddish meteors.