Perfect Perseid pleasure
Dare I say the days of summer are starting to wane in Butler. The back-to-school ads are running full-bore on TV, and the meaningless NFL preseason games have begun.
One good thing you can rely on this time of year is the annual Perseid meteor shower, one of the best of the year. There are about a dozen meteor showers a year, but the Perseids are special because they’re not only prolific but you can watch them comfortably, unless the weather goes really haywire.
The show has been going since the beginning of August and it peaks this week, especially this coming Wednesday night into very early Thursday morning, Aug. 12 to 13. The absolute best viewing will be after midnight, around 4 a.m., before morning twilight kicks in.
The Perseids are extra special this year because there’s no moonlight interference in the early morning hours, leaving us with dark skies. If you can get out into the countryside or at least the outer ring of suburbs for the really dark skies all the better.
You might see 50 to 80 meteors or more “shooting stars” per hour. Maybe more than one every minute! Even in more lit urban areas you’ll see at least five to 10 an hour with a little perseverance.
The Perseids are called the Perseids because all the meteors seem to emanate from the general direction of the constellation Perseus the Hero. Perseus is said to be the radiant of this meteor shower.
Perseus the Hero rises high in the northeastern sky in the early morning hours. Whatever you do, though, don’t restrict your meteor search to just that part of the sky. If you do, you’ll miss a lot of them.
My advice for watching the Perseids — or any other meteor shower — is to lie back on the ground or a reclining lawn chair and roll your eyes all around the sky.
Watching a meteor shower is a great way to spend a summer night, and watching with family and friends is even more fun. The Perseids are famous for the number of meteors you see, but most of them are faint and rip across the sky rapidly, so the more eyes watching the big sky the better!
Meteors are often called “shooting stars.” They do look like stars, but they’re actually just grains of dust and pebbles. The biggest ones may approach the size of small walnuts.
This is all debris left behind by comets that have passed by Earth and the Sun. Comets are basically dirty snow/ice balls that partially melt when they get close to the sun. Debris from these partially melted comets is left in their wake, and gravity between the particles keeps the debris trail intact.
Meteors from meteor showers are best seen after midnight because then, our part of the Earth is heading directly into the debris trail, as you can see in the diagram.
The debris trail that causes the Perseids comes from the Comet Swift-Tuttle, which passes through this part of our solar system about every 130 years and was last seen in 1992. Because of that recent visit, the Perseid meteor shower was even more prolific in much of the 1990s, but, even now, it’s still a great show.
There were some who thought Swift-Tuttle could collide with Earth in 2126, but that’s been downplayed by many astronomers … stay tuned, though!
In the meantime, tiny pieces of Comet Swift-Tuttle will slam into our atmosphere at speeds over 40 miles per second, easily incinerating them before they can get anywhere near you. Most bits of this debris burn up around 40 miles high.
There’s no way you can see these bits burn up at that height. How could you? So where does the light come from? The answer is the process of ionization.
These debris particles are zipping through our atmosphere so fast that the column of air they’re going through is being destabilized. Zillions of electrons from atoms that make up Earth’s atmosphere get temporarily bounced away from the nucleus of zillions and zillions of atoms. As these electrons bounce away and then back, they produce energy as bright light.
In fact, a lot of meteors you see leave a trail that can take a few seconds to fade. What you’re seeing is the column of air that the meteor ripped through stabilizing and getting its act back together.
I strongly advise that you get your act together and catch the Perseids. It’s one of Mother Nature’s best shows of the year. Don’t forget the bug juice!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is also the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and at adventurepublications.net. Contact him at mikewlynch@comcast.net.
