Sky Watch: August's Perseid meteor shower
I always enjoy August because it's when we're approaching the annual Perseid meteor shower.
You see, it was the ancient Chinese sky watchers who first documented this shower in 36 AD and wrote that "more than 100 meteors flew thither in the morning." Of course, they used a corresponding word in Chinese, but you get the idea.
debris expelled by Comet Swift-Tuttle. As this cometary litter plows into our upper atmosphere, it is incinerated and produces meteors. Most are no larger than a grain of sand and are extinguished at heights of 50 miles or higher.
Stand outside during any meteor shower and you'll see meteors (also called falling or shooting stars) all over the sky, but if you trace their paths backward, you'll discover that they all appear to come from one specific location in the sky. This is called the shower's "radiant" and is often named for the constellation in which it lies.
And that's why this month's shower is known as the Perseids: its radiant lies in the direction of the constellation Perseus. Any that appear not to radiate from this direction are called "sporadic" meteors and are flecks of dust, not part of the Swift-Tuttle swarm.
This year's peak occurs during the night of August 11, and the morning of August 12. Typically, we spot most meteors before dawn because it's during those hours that we face the direction of our planet's motion and can watch as we sweep up meteoric particles. And during its peak hours, stargazers under a dark rural sky should be able to count as many as 60 to 100 every hour -- all appearing to come from the direction of Perseus in the northeast.
.Be sure to take a lawn chair or sleeping bag, a blanket or hot chocolate to keep warm, and gaze up toward the northern and northeastern sky.