Sky Talk August 2008: Meteor Month

For many stargazers, this is “meteor month” — so named after the famed Perseid Meteor Shower that peaks each year during the second week of August. And while not the richest of these annual celestial fireworks displays, it’s certainly the best-known and among the most reliable of them all. The only uncertainty involved in viewing such events (aside, of course, from clear skies!) is if the presence of a bright Moon will offer interference. This time, the answer is “yes, it will” or “no, it won’t” — depending on what time of night you go looking.

The Perseid meteor shower will occur this year on the evening of August 11th throughout the morning of August 12th. This display is expected to produce as many as 100 “shooting stars” an hour at its peak as seen from from a dark sky location, with about half as many visible from urban locations. The number of meteors will increase steadily throughout this period for a number of reasons. One is that a 10-day-old gibbous Moon will brighten the sky until it sets around 2 a.m. local time. Another is that the radiant — that point from which the meteors appear to radiate toward us — continues to rise ever higher in the sky as the night progresses. For this shower, it’s located in the constellation Perseus, located very low in the northeast after darkness falls on the 11th. Using your Edmund Star and Planet Locator to first identify it, see how it rises higher and higher by setting the star-disk to later and later hours, being nearly overhead by the time dawn approaches. This year maximum activity is predicted to occur after sunrise on the 11th (around 7:30 a.m. EDT), so for that reason the numbers seen will also continue to increase towards dawn.

There’s yet another and largely unsuspected factor at play in this and all meteor showers. During the evening hours we’re on the side of our spinning Spaceship Earth that’s essentially facing away from the direction the meteors are approaching, and so they have to “catch up” with us. But after midnight we’re turned completely toward the direction of the radiant, causing them to slam into the atmosphere at much higher speeds — resulting in many more being seen and those that are seen being brighter. So losing some sleep to stay up late watching meteors (or setting the alarm clock and getting up in the hours after midnight) is always worth doing.

For optimum coverage in observing meteor showers, face toward the radiant while at the same time concentrating your attention on the sky overhead, preferably reclining comfortably on a lawnchair or heavy blanket and pillow. And while this is basically a naked-eye activity since it’s important to canvass as large an area of sky as possible, using your Edmund binoculars is also encouraged for following the trails or “trains” often left behind by many of the brighter meteors. For an added thrill, point them at the radiant itself — you may be lucky enough to see a few meteors coming directly at you, suddenly appearing from out of nowhere as brightening stars!

–James Mullaney
Former assistant editor at Sky & Telescope magazine and author of five books on stargazing.


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