The warm evenings of August are an excellent time to get out under the stars and enjoy the natural sky. Around the 13th of the month, it may be worth sitting up a little later to catch one of the year’s best meteor showers, the Perseids. The Perseids (purr-SEE-idz) are what inspired me, as a young lad, to see what the heck this astronomy thing was all about.
This meteor shower is reliable and prolific; if you make the effort to get out, it will make the effort to entertain. It is named for Perseus, the constellation the meteors appear to originate from, currently found low in the north east. To help keep you from getting bored, there are also six lesser showers on at the same time; these meteors will be slower, and appear to come from different areas of the sky.
The actual shower runs for nearly a month, with the actual peak of the stream, when the most meteors will appear, being the evenings of August 12th thru 14th. For the Perseids, 60-100 meteors per hour are the norm. This year, the Moon co-operates and stays out of the way, leaving us with perfect dark skies for meteor watching.
Meteor showers are best viewed with your eyes alone, and the best time is just after midnight. Bring bug spray, and a warm jacket or blanket; it can get surprisingly cool August nights. Bring friends; it’s a great group activity. Pick a dark spot away from lights, trees, buildings and other tall obstructions that block your view of the sky. Lie back in a reclining chair or on a blanket facing ‘north-east-ish’, and let your gaze wander. As your eyes gradually dark-adapt (about 15-20 minutes), meteorites will start to appear. Optionally, have binoculars handy for closer glimpses at interesting stuff you’ll spot in passing. Note that looking at your smart phone’s bright screen will destroy your night vision immediately, so resist the urge to update your Facebook page.
Meteors are dust and bits of small rock tossed off, over millennia, by passing comets. Perseid meteors enter the atmosphere at a speedy 60 kilometres per second and totally burn up at an altitude around 80 kilometres. For the Perseids, the parent body is Comet Swift-Tuttle which crosses the Earth’s orbit, and drops off more stuff, once every 133 years, most recently in 1992.
Swift-Tuttle’s orbit is such that it will almost certainly eventually hit either the Earth or the Moon, although not for a while. There will close misses August 5th, 2126, and again in September of 4479 (0.0001% chance of it hitting us). Described as “the single most dangerous object known to humanity”, with a diameter of 26 kilometres, it’s impact would be roughly 27 times that of the event that wiped out the dinosaurs.
But, for now, be happy. This great annual shower is something worth staying up late for.
