The year’s best meteor shower, the Perseids, peaks during the evening of Aug. 12 and Sunday morning, Aug. 13.
The crescent moon will rise at 2:47 a.m., but Luna should not substantially affect the view because it is only 8% illuminated.
The best time to observe the Perseids is during the early (and I do mean early) morning — from just after local midnight on Sunday until the rising sun spoils the view.
Meteors are streaks of light that flash across the sky. They usually last a second or so. They happen because bits of space debris, most about the size of grains of sand, burn up in Earth’s atmosphere.
When you sit back to watch for meteors, you see pieces of solar-system detritus heat up and burn in a bright streak of light, careening across the sky at 37 miles per second.
You are not seeing the actual speck burn up. Instead, you are seeing the object heat the surrounding atmosphere. That process causes the atmospheric gas to glow in a long train that follows the path of the speck of debris.
On any night, meteor shower or not, you’ll see at least five meteors per hour if you’re observing from dark, rural skies where the glow of streetlights (or the moon) doesn’t wash out the view.
Meteor showers happen when Earth passes through a cloud of dust laid down by a passing comet, essentially a dirty ball of ice. Showers occur about the same time every year because Earth returns to the spot in its orbit where the debris cloud hangs out.
The comet in question here is Swift-Tuttle, a scant 16 miles wide.
As it passes close to the sun, where we are, the sun’s energy heats up and vaporizes the ice on the comet’s surface. The dust, rock, and dirt embedded in the ice are thus released, leaving a dusty, dirty, rocky trail that our Earth passes through quite regularly every year.
Swift-Tuttle last passed nearby Earth during its orbit around the sun in 1992. Its next pass will be in 2126.
1. Go to dark, rural skies away from city lights.
2. Sit in a lawn chair and stare in the direction least polluted by city lights on the horizon. The meteors seem to originate from the constellation Perseus, which appears on the horizon at about 10 p.m. local time, but meteors will appear all over the sky. Straight up is always good if you have a chaise lounge and the innate ability to stay awake horizontally.
3. Use your peripheral vision to see as much of the sky as possible.
4. Listen to me now. The following point is essential. Please stick it out until morning twilight. You’ll see a lot more meteors during the predawn hours on Sunday than you will just after dark on Saturday.
Here’s why: Earth travels 67,000 miles per hour around the sun. Before local midnight, you are facing away from the direction of Earth’s motion. Consequently, the specks of space crud have to play catch up with Earth to hit it. After local midnight, you are facing in the direction of Earth’s orbital motion. Earth is doing most of the work by slamming into the space debris.
I call this principle the Bug on the Windshield Effect. On a meteor-shower night, Earth is like your car traveling through a swarm of bugs. You won’t see many bugs on the back windshield. Wait for Earth to turn into the direction of the swarm.
Because of daylight saving time and our position in the time zone, local midnight occurs at about 1:30 a.m. Between 3 and 5 a.m., you may see as many as 60 per hour. The best display almost always happens in the last hour before morning twilight spoils the view.
5. Take along a blanket and some bug repellent. It gets chilly at night, and you don’t want the skeeters to think of you as a delightful breakfast buffet.
6. You won’t see any meteors if the sky is cloudy. If the forecast is iffy, try the night before or after. The Perseids are active from mid-July to late August. Looking for them on the peak night maximizes the number of meteors you will see, but you’ll see more than a few on other nights.
Tom Burns is the former director of the Perkins Observatory in Delaware.