Curious Nature: Different kind of ﬁreworks
December 31, 2012
As we approach the annual evening of festivities that marks the start of another trip around the sun, fireworks are often a part of the revelry. But for those who prefer things a little bit quieter, there are some other, secret fireworks that may soon be lighting up the night skies. On Thursday, the Quarantid Meteor shower will be reaching its peak and is expected to be visible in the northern and western part of the United States (that’s where we live, for those of you who are geographically challenged). Though slightly less famous than their summer cousin, the Perseids, the Quarantids are worthy of their own place in the sky.
But what is a meteor shower? Also known as shooting stars, meteors are bits of rock that have entered the Earth’s atmosphere. These specks from space have an interesting system of classification with names that change depending on location. Rocks shooting through space are known as meteoroids, and while some orbit the sun on their own, many are pieces from comets, which shed particles as they orbit the sun. Once these particles enter the Earth’s atmosphere, they are called meteors, while those that make it all the way to the ground are termed meteorites. And then the grand finale of these individual skylights, a meteor shower occurs when the Earth passes through a cluster of meteors, often set loose from the tail of a comet.
Meteors appear as a streak of light across the night sky, lasting only a fleeting second or two. What we are actually seeing is not the pea-sized piece of rock itself but the reaction of the gases in our atmosphere as they are heated by the friction from the rapidly moving object. Most meteors are completely incinerated somewhere between 60 and 80 miles above the Earth’s surface, leaving us to marvel at their short-lived brilliance if we’re lucky enough to spot them.
Watching a meteor shower might seem fairly straightforward, but there’s more to it than you think. First, meteors tend to peak after midnight, with the most and brightest lights showing up between midnight and dawn. The reason for this has to do with the Earth’s rotation. During the first part of the night, after sunset, we are basically on the trailing edge of our planet as we travel around the sun, and any meteors that we see have had to “catch up” with the Earth. But after midnight, we are on the side of the Earth that is overtaking slower particles, resulting in more meteors that appear bigger and brighter. Another important factor in spotting meteors is the brightness of the moon. This year, the gibbous moon will rise shortly after midnight on Thursday, coinciding with the meteor shower’s predicted peak and possibly making it difficult to see.
The Quarantid meteor shower differs from the Perseids and other showers in that it has a relatively short peak period, lasting only a few hours, although the number of meteors per hour (60 to 80) is similar. This fact, combined with the Earth’s rotation and the bright moon, reduces your chances of seeing the night sky light up like the Fourth of July. However, if you still want to give it a try, meteor showers are best watched from the comfort of a lawn chair and sleeping bag away from city lights. Set your alarm for after midnight, and make yourself cozy as you watch the skies to the north.
Jaymee Squires is the graduate programs director at Walking Mountains Science Center.