Elizabeth Jeffery, Ph.D., is an astronomer and researcher at the Space Telescope Science Institute in Baltimore City.
If wishes made on shooting stars come true, this could be your lucky weekend. Early Saturday morning marks the peak of the annual Perseid meteor shower.
Few things give even a casual star gazer as much heart-jumping excitement as spotting a meteor. Meteors, sometimes called shooting or falling stars, are actually not stars at all. A meteor is created when a tiny piece of space junk (for example, a bit of dust or rock) enters the earth's atmosphere. As this small piece of debris flies high through the air, it encounters friction that makes it so hot it will burn up. As a result, a meteor appears as a quick, bright streak across the sky, and will then disappear. The brighter and longer the streak, the bigger the rock or dust particle that burned up.
On an average night, if you are away from city lights, with a dark, moonless sky, you will see an average of six random meteors an hour (mostly faint ones). But several times a year, we are treated to a meteor shower. Meteor showers are when the number of meteors we see are considerably greater than average. These additional meteors will also appear to be coming from approximately the same spot in the sky.
The predictable timing of some meteor showers is due to some of Earth's messier neighbors, comets. Comets go around the sun, just as the Earth does, but follow a different path. Sometimes comets will cross the orbit of Earth, and when they do, they leave behind them a trail of dust, rock and ice. Every time the Earth passes through this dirty spot (even after the comet is long gone), there is an increased amount of debris that enters our atmosphere and burns up, creating more meteors.
The comet that created the reserve of space junk for this weekend's shower is known as Comet Swift-Tuttle, and it is on an orbit that takes roughly 133 years to complete one trip around the sun.
A meteor shower is named after the constellation where the meteors appear to be coming from. This month's shower will appear to be coming from the constellation Perseus, hence its name—the Perseids. The Perseid meteors are expected to appear at a rate of 60 per hour.
You don't need any fancy equipment to view a meteor shower. In fact, it's better if you don't use a telescope or binoculars to watch for meteors because you want to be able to see a large area of sky all at once. Meteors will appear unexpectedly, and sometimes you will see one out of the corner of your eye, so you don't want anything narrowing your vision. All you have to do is lay back on a blanket or a lawn chair in a spot away from city lights and watch the sky.
One common misconception is that you can only see a meteor shower on the peak day and at a specific time. Higher meteor rates will be visible for a few days on either side of the peak. In fact, this year it may be to your advantage to go out a day or two before the Aug. 13 peak. This weekend's Perseids peak happens to coincide with the full moon and the moon will wash out many of the meteors, making them hard or impossible to see. If you go out a few days before the peak, early in the morning when the moon has set but the sun hasn't come up yet, you will be able to see more meteors.
So get out and enjoy our sky's natural fireworks!