Sky Watch: The Perseids are coming

Few sights are as thrilling as the fiery spectacle known as a meteor -- also called a "shooting" or "falling" star. Astronomers can't predict exactly when or where a meteor will appear, but each year during mid-August sky watchers flock to the countryside and mountains to view one of the year's most reliable displays: the Perseid meteor shower.

This year will be no exception; the shower's peak will occur on the night of Sunday, Aug. 11, and the pre-dawn hours of Monday, Aug. 12, but you will see early meteors from this shower throughout the weekend.

Often a bright meteor will start my phone ringing from people stunned by the sight, but these are not all that uncommon. Our region of space is littered with dusty particles called meteoroids -- most no larger than a grain of sand. As one slams into our upper atmosphere at more than 100,000 miles per hour, it disintegrates in a quick, but dramatic, burst of light. An observer can typically see three or four random (or sporadic) meteors every hour falling from various directions on any clear dark night.

There are, however, times when our odds of seeing meteors improve, and next weekend will be one of those times. That's because our planet will be carrying us on our annual journey through the swarm of dusty debris expelled by the slowly disintegrating Comet Swift-Tuttle.

After watching for a while, you'll notice that these meteors appear to fall all around the sky, but if you trace their paths backward you'll discover that they all appear to radiate from one location in the sky. This point is the shower's radiant and is often named for the constellation in which it lies.

And that's why this month's shower is known as the Perseids: Its radiant lies in the direction of the constellation Perseus. Any meteors that appear not to radiate from this direction are called sporadic meteors, and are random flecks of dust not part of the Swift-Tuttle swarm.

So why is it that astronomers always suggest that you will see more meteors before dawn? It's quite simple, really. Since the Earth is plowing into this cloud of dusty debris, one can liken the phenomenon to a car encountering a swarm of bugs on the highway. The front windows receive the brunt of the impacts, while the side and back windows hardly get any.

The same is true as the Earth whirls through space. Our best view of the shower comes when we're peering out the Earth's "front window" -- and that comes just before dawn.

For the best view, many people camp in the mountains, deserts or countryside, or set up on side, rural roads away from traffic. And no equipment is required either; all you need to enjoy the shower is your eyes, but binoculars might be helpful to check out long smoke trails left behind by any exploding fireballs. Be sure to take a lawn chair or sleeping bag, a blanket or hot chocolate to keep warm, and gaze skyward.

And if you'd like to try your hand at capturing some meteors with your camera, check out these quick tips on my website: dennismammana.com/skyinfo/phototips/skyphoto_meteors.htm