Perseus Throws a Party of the Year
The prolific Perseid Meteor Shower peaks this year on Monday, August 13, so we can expect to see plenty of meteors all weekend starting from the 10th of August till Monday night.
Within a couple of nights before and after the peak date, the quantity will be reduced somewhat, but still worth looking for. We expect a fantastic show this year. The moon will reach its new phase two days before the predicted shower maximum. This means that the very slender crescent moon will set in the early evening and will not interfere at all with viewing this year’s display.
Meteor showers are annual events that occur when the Earth’s orbit passes through zones of debris left by multiple passes of periodic comets. (The analogy would be the material tossed out of a dump truck as it rattles along. The roadway gets pretty dirty if the truck drives the route a number of times!) Over the centuries, or longer, the dust-sized and sand-sized (or larger) particles accumulate and spread out a bit. When the Earth encounters them, the particles are caught by our gravity and burn up as they fall through our atmosphere at speeds on the order of 200,000 km/h. The duration of a meteor shower depends on the width of the zone, and the intensity depends on whether we pass through the densest portion, or merely skirt the edges.
The source of the Perseids material is thought to be a 133 year period comet named Comet 109P/Swift-Tuttle. The active period for this shower is July 13 through August 26, so keep an eye out for them beyond this week. This shower is known for producing 60–80 meteors per hour at the peak — many manifesting as bright, sputtering fireballs!
While visible anywhere in the night sky, meteors will appear to radiate from a location in the sky (called the radiant) between the constellations of Camelopardalis (the Giraffe) and Perseus (the Hero), which gives this shower its name. The radiant is low in the northeastern sky during mid-August evenings — and nearly overhead by dawn. Meteor showers are best observed in the dark skies before dawn, because that’s the time when the sky overhead is plowing directly into the oncoming debris field, like bugs splatting on a moving car’s windshield. When the radiant constellation is overhead, the entire sky is available for observing.
The highest Perseid meteor rates this year are expected to occur on from Sunday night into Monday morning August 12–13, when the Earth will be the closest to the core orbit of comet 109P/Swift-Tuttle and its debris trail. If you begin to watch after dark on Sunday evening, you might catch very long meteors that are skimming the Earth’s upper atmosphere. These are fewer, but spectacular. As the night rolls on, the radiant of the meteors will rise higher in the sky, revealing more meteors because they are no longer hidden by the bulk of the Earth. The absolute best time to view is around 4 am local time when the radiant will be almost overhead and entire supply of meteors will be available for viewing.
For best results, try to find a safe and very dark viewing location with as much open sky as possible. Even a 30 minute drive to a park or rural site away from big city light pollution will help a lot. You can start watching as soon as it’s dark. Don’t worry about watching the radiant. Bring a blanket for warmth and a chaise to avoid neck strain, plus snacks and drinks. Try to keep watching the sky even when chatting with friends or family — they’ll understand. Call out when you see one; a bit of friendly competition is fun!
Don’t look at your phone or tablet — the bright screen will spoil your dark adaptation. If you can, minimize the brightness or cover the screen with red film. Disabling app notifications will reduce the chances of unexpected bright light, too. And remember that binoculars and telescopes will not help you see meteors because they have fields of view that are too narrow. Good hunting!