Meteor astronomy is generally neglected by amateurs. This is unfortunate as the field offers an excellent opportunity to contribute observations of scientific value and provides many enjoyable evenings of observing. There are only a few professional astronomers active in meteor research today, therefore the field relies heavily on the amateur for data. This data collected by amateurs can provide astronomers with information on the origin and evolution of meteoroids, which in turn sheds light on the origin and evolution of our solar system. With minimal equipment, and knowledge of a few basic concepts, you can begin a lifelong pursuit of meteor observing.
Meteors typically are small particles, normally no larger than a grain of sand, that enter our atmosphere at speeds of up to around 70 kilometers per second. They become visible at an altitude of about 100 kilometers due to their impact with the atmosphere. Most particles will evaporate from the effects of heat well before reaching the surface of the Earth. Those that do reach the surface of our planet are known as meteorites.
Although meteors can be seen any clear night, your chances of seeing greater numbers will increase if a few points are kept in mind. Moonlight and light-polluted skies wreak havoc upon meteors. Therefore, it is always best to observe when the moon is absent from the sky, as well as from the darkest skies possible.
Another important consideration is the time of night the meteor watch is held. Due to the rotation of the Earth, it's best to observe in the early morning hours. At this time, an individual is facing the direction the Earth is traveling in its orbit. Meteors will then collide with our atmosphere. At other times, meteors must travel at a speed that allows them to overtake the Earth. This situation is similar to a car traveling through a snowfall where more snowflakes will strike the front windshield rather than the back.
There are two broad groups of meteors. Those that arrive from random locations in the sky are termed sporadic, while others that appear to radiate from a particular region of sky come from meteor showers. The Perseids of August are an example of a meteor shower.
Sporadic meteors, also known as the sporadic background, generally produce only about 5 to 10 meteors per hour, but actually make up the bulk of meteors entering our atmosphere. It is believed that sporadics originate from unknown minor showers and meteoroids (objects which have not yet entered Earth's atmosphere) that once belonged to a shower but have left their original orbit. To increase your chances of observing these meteors, it should be kept in mind that they exhibit a diurnal variation where more occur before dawn than after dusk. There is also an annual variation where more occur in the second half of the year.
The highlight for meteor observers during any year is the nights when meteor showers are active. Although each shower is somewhat different, they normally last for several nights with a peak of activity occurring on a specific date. Chances of observing meteors are greatly increased on the night a shower is active as rates can range to 50 or more per hour depending upon the shower. These meteors can be distinguished from the sporadic background by the fact they radiate from one particular region of the sky known as the radiant. The Geminids of December, for example, appear to come from a location near the star Castor.
Back to Table of Contents