| Home | Articles | Guide to Observing | Tour of the Constellations | Book Reviews |
A meteor is popularly called a "shooting star" although in reality it's about as far from a star, which consists of billions and billions* of tons gas in a massive fusion reaction, as one can imagine. A meteor is simply a speck of dust entering the Earth's atmosphere. As the speck passes through the atmosphere, it reacts with the atmosphere and creates an ionized trail of light that can be seen from the Earth's surface. The dust speck is called a meteoroid before it enters the Earth's atmosphere. Most meteoroids are quite small but some are so large that they partially survive even after passing through the Earth's atmosphere. They're called meteorites.
Meteors can be seen every night of the year. But on occasions, they come in large numbers and are called "Meteor Showers". For instance, every year around this time (August 12) there is usually a major meteor shower which is called the "Perseids" because it seems to be emanating from the constellation Perseus. Why always on August 12th? In 1862 a major comet passed crossed the Earth's orbit, leaving a trail of "cosmic bread crumbs" behind. This dust has remained suspended across the Earth's orbit since then. Whenever the Earth crosses this spot in its orbit, the dust left behind by the comet enters the atmosphere causing a meteor shower. With minor variations, meteor showers take place the same time each year.
The most important thing about observing meteors is finding a good dark location. If the Moon is above the horizon or you're too near city lights it will be very difficult to spot them. In general the best time at night to see meteors is shortly before sunrise while the sky is still totally dark.
Although most meteors are caused by small specks of dust, occasionally something larger will enter the Earth's atmosphere and cause a fireball. A fireball is considerably brighter than an ordinary meteor and will move a more slowly across the sky.
* As a fan of Carl Sagan, I had to use that expression at least once.
Ophiuchus