Meteor showers are relatively common occurrences, with several scheduled ones occurring annually, and others occurring on a seemingly random basis. We’ll concentrate most of our discussion on the annual showers; however in most cases, the information herein will apply to all such events.
Before we delve too deeply into the types of meteor showers, what they are made of, and where they come from, it would behoove us to know some key definitions. You may have heard the terms “meteor”, “meteoroid”, and “meteorite”, and either assumed they meant the same thing, or not known the difference. These terms refer to the same object, but are not interchangeable. The key to knowing which to use is WHERE the object is.
A “meteoroid” is an object that is floating through space. When a meteoroid enters the atmosphere of the earth (or any other object with one), it becomes a “meteor”. Those lucky few that actually manage to reach the surface are “meteorite”. So, what you see and associate with the term “falling star”, is in fact, at that moment, a “meteor”. Before then, it was a “meteoroid”, and may become a “meteorite”. Almost everyone has seen a meteor; a very precious lucky few have found a meteorite.
Sporadic meteoroids, flying in different directions, hit the earth every day. On any given cloudless night, if you stand still, and look at a given section of the sky long enough, you’re likely to see one or more meteors, as their “lives” meet a fiery end as they burn up from all the friction they generate rubbing against our air. It’s amazing, really, to think that the object that causes such a bright flash is generally only the size of a grain of dust, or little more.
A meteor “shower” then, is simply an event in which a much greater than average number of meteors are striking the earth simultaneously, and generally they all tend to come from the same direction. The annual showers are all named after the constellation of stars from which they appear to generate. For example, the Perseid shower, which occurs every August, is so named because it appears to be centered on the constellation “Perseus”, named after a hero of Greek Mythology. The Perseids are probably the most famous meteor shower, but there is also a Leonid (constellation Leo) shower in November, the Geminid shower (constellation Gemini) in December, and several others.
Of course, it should be clarified that these particles do not REALLY come from these constellations as they appear to. The stars that make up those constellations are much, much too far away to send us their dust every year. They just appear to because the stars form the “backdrop” on our local system. It is similar to suggesting that the moon is “in” the constellation Pisces on a given night. It is of course nowhere near those other stars, but they just appear in the same section of sky from our perspective.
So, why do we typically see random and sporadic meteoric activity most of the year, but these specific annual showers on predetermined intervals? The answer lies in comets. These mysterious object release dust and gas every time they approach the sun, in the form of a beautiful “tail” that makes the comet unique. Once released, that dust doesn’t just “disappear”, but instead follows in the orbit path of the comet. So, each year, when earth’s orbit carries it through the orbital path of a comet, we get all the dust from the dust trail, and since it’s all coming from the same area of the sky, it all appears to come from the same place. That place is called the “radiant point”, sometimes shortened to just “radiant”.
Now that you have a good idea of what a meteor shower is, and why they appear as they do, let’s discuss some practical tips on viewing one. Let’s pick the popular Perseid shower upon which to concentrate. One reason it’s popular is that it occurs in the summer months, making a long stay outdoors in the middle of the night much more pleasant than it might be in, say, January, for those of us in the Northern Hemisphere. Just don’t forget some bug spray!
One of the primary turn-offs for people wishing to view these amazing events is that the peak viewing times are very late at night, often between 2-4am. The reason is that the comet path is going to be opposite the sun from us. In other words, we see the most activity when our location on earth is exactly opposite that of the sun, so several hours after sunset, and several hours before sunup.
If you’re interested in seeing one, though, this is a price you must pay. Trust me, though, it’s worth it! A little bit of preparation before going to bed the night before can make your awake time as productive as possible. What you want to do is familiarize yourself with the general area of the sky that will be the focal point of the shower, using a star chart or other source. You also want loose, comfortable clothing, like sweats or similar, bug spray (if in summer months), a blanket or two to lay on, and a pillow to rest your head on, because you’ll be staring UP for a long time. Once you get all your gear together, set your alarm and get a few hours’ sleep before viewing time. Or not, if you’re a late owl type and don’t have to work the next morning!
Depending on the visibility in the desired direction in your neighborhood, you may have a little bit of traveling to do to get to a good spot to see the shower. There are two key factors in finding a good viewing location: minimal amounts of light interference (light “pollution”), and an unobstructed viewing area in the direction of the shower.
Once you get into position, get yourself comfortable, and watch the area. A good shower can reach peaks of up to 100 sightings an hour. It may not sound like a lot, only 1 or 2 a minute, but when you’re out there, you’ll understand. It’s definitely something every person should do once in their lifetime. Much like watching a particularly beautiful sunrise or sunset, witnessing a good meteor shower is a truly special event.
