Jimmy Westlake: Catch a falling star this weekend
August 6, 2012
The annual Perseid meteor shower is under way and is expected to peak before dawn Sunday. The Perseid meteor shower is the "Old Faithful" of meteor showers because, under good sky conditions, it dependably produces 60 or more "falling stars" per hour at its peak.
Sometimes referred to as "St. Lawrence's Tears," Perseid meteors have been observed every August since at least 258 A.D. That's when the Romans martyred a Christian deacon named Laurentius on a hot gridiron. As Laurentius' family carried away his body, they noticed a number of bright streaks shooting across the sky, and they marveled at the miracle, thinking the streaks were the fiery tears of Laurentius falling from heaven. Centuries later, people the world over continue to marvel every August at the sight of "St. Lawrence's Tears."
In 1862, American astronomers Lewis Swift and Horace Tuttle co-discovered a comet that now bears their names. Italian astronomer Giovanni Schiaparelli pointed out that the particles that cause our Perseid meteors orbit the sun in the same path as Comet Swift-Tuttle. That was the first indication that comets could be the source of our annual meteor showers.
We now know that the Perseid meteors are produced when tiny bits of dust shed by Comet Swift-Tuttle enter the Earth's atmosphere at 130,000 mph and burn up as fiery meteors about 60 miles over our heads. These dust particles are so tiny that you easily could hold 1,000 of them in the palm of your hand.
Perseid meteors can be seen in all parts of the sky, but their trails all will point back toward the constellation Perseus in the northeastern sky. Saturday is the night of peak activity, but plenty of Perseid meteors can be seen for about a week on either side of that day. You always will see the most meteors between midnight and dawn because that's when the spinning Earth has you facing the direction from which the meteors are streaming.
Perseid meteor-watching makes a great family activity. Take the kids and find a nice, dark campground, roll out the sleeping bags and watch the fireworks. See who can count the most meteors or spot the brightest one. This year, the 24-day-old moon will rise at about 1:30 a.m., sandwiched between the dazzling planets Jupiter and Venus, but its thin, sunlit crescent shouldn't interfere with watching dozens of meteors shoot across the sky.
Sky watching just doesn't get any better than this.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published all across the world. Check out Westlake's astrophotography website at http://www.jwestlake.com.