Earlier this month, we had the pleasure of catching the Perseids, the annual mid-August meteor shower. We hadn’t planned our summer vacation to coincide with the showers, which occurred this year between the end of July and the middle of August. We were just lucky to be on a lake with a wide-open view of the night sky — and even luckier, given the weather this summer, to have a couple of clear nights to look for these “falling stars.”
Meteor showers aren’t actually falling stars. They begin as cosmic debris that trails along behind comets and “dirty snowballs,” in which the dirt can be as small as a dust mote and the “ball” can be frozen water, but also frozen methane or ammonia. When a comet’s orbit passes near the Earth, this debris can enter the Earth’s atmosphere, where it heats up and vaporizes. What we see is a streak of light that typically lasts less than a second. You can see vaporizing meteorites any time of the year, but at particular times there are so many that they create a “shower” of light in the night sky.
Some annually recurring showers have acquired names, typically for the constellation in the part of the sky where they appear. The Perseid shower, which peaks each year on August 12, comes from the Swift-Tuttle Comet and appears near the constellation Perseus.
If you catch the Perseid shower at its peak, you can sometimes see more than a meteor a minute. We did our watching a night early, combining it with a late-night dip in the lake. (Virgil had to do his watching from the dock, to protect his cast. See “What we talk about when we talk about risk.”) Jim and Ursula and I lay on our backs and watched the stars. Jim caught the first meteor and told Ursula where to look. A few minutes later we all saw a glowing bright line seeming to fall away from the sky. Ursula oohed as if she’d just seen fireworks, which in a way she had.
We’re looking ahead, now, to the Orionids, a meteor shower associated with the Halley Comet that appears around the constellation Orion and starts in mid-October.
The image at the top of this post comes from the article “The Perseids Are Coming” by Dr. Tony Phillips of Science@NASA, which also contains a short description of the Perseids.
The Stardate site gives viewing tips and dates for 2009 meteor showers.
“Great Kids, Great Outdoors” is an AMC Outdoors blog, written by Kristen Laine.
Labels: astronomy, Kristen Laine, outdoor education, stars