In mid-August, our planet will be carrying us on our annual journey through the swarm of dusty debris expelled by the slowly disintegrating Comet Swift-Tuttle. (Creators.com illustration)
Few sights are as thrilling as the fiery spectacle known as a falling star, also called a shooting star or meteor. Astronomers cannot predict exactly when or where a meteor will appear, but each year during mid-August, skywatchers head away from the city lights 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 during the early morning hours of Wednesday, Aug. 12, but stargazers will surely spot a few early meteors from this shower over the next week or so.
Often, a bright meteor will cause my phone to start ringing from people stunned by the sight, but meteors are not all that uncommon. Our region of space is littered with dusty particles called “meteoroids,” most no larger than a sand grain. As one slams into our upper atmosphere at more than 100,000 mph, 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 dark night.
There are times when our odds of seeing meteors improve, however, and mid-August is one of them. That’s because our planet, Earth, 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 most appear to radiate from one location in the sky. This point is called the shower’s “radiant” and is often named for the constellation in which it lies.
This is why the August 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 that are 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. The Earth is plowing into this cloud of dusty debris; this phenomenon is similar 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. This August, the last quarter-moon will appear in the early morning sky, and its light may block from view some of the fainter meteors.
For the best view, many people camp in the mountains, deserts or countryside, or they set up on rural roads away from traffic.
No equipment is required either; all you need to enjoy the sky show 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 and hot chocolate to keep warm — yes, even in the summer — and gaze skyward.
— Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at [email protected] and follow him on Twitter: @dennismammana. The opinions expressed are his own.