Meteors (or "shooting stars") are produced by small objects burning up in the Earth's atmosphere. Through chance encounters with the Earth, meteoroids (small particle in space) enter the upper atmosphere. Collisions with air molecules heat the object, which normally vaporizes 80 to 100 kilometers above the Earth. These are called sporadic meteors, and they enter the Earth's atmosphere at random. Meteors are typically no larger than grains of sand, however, occasionally a baseball size object will streak across the sky producing a brilliant fireball. Any meteor which survives this fiery journey through the atmosphere and reaches the Earth's surface is called a meteorite. Meteorites are meteor remnants which reach the Earth's Surface.
At certain times of year, the Earth encounters a swarm of cometary dust. This debris is spread out along the along the orbital path of a parent comet. For a period of a few days or even weeks, there is concentration of meteors emanating from a small area of the sky, known as the radiant. There are about a dozen such meteor showers each year. The showers are named for the constellation or bright star which is near the radiant, e.g. the Orionids seem to radiate from the constellation Orion. Meteor showers are best seen on clear, moonless nights in the late hours after midnight.
Quadrantids
Quadrantids are named after the old constellation Quadrans Muralis. They are seen in the first week of January, and the radiant is in the constellation Bootes. The meteors are of medium speed often blue in color. The peak activity last for a few hours.
Lyrids
The Lyrids are seen in mid-March and are associated with Comet Thatcher of 1861. The meteors are generally swift, and many appear as brilliant streaks across the sky.
Eta Aquarids
The Eta Aquarids are associated with periodic Comet Halley. They are seen in the first week of May. The meteors are very swift, often appearing in persistent trains.
Capricornids
The Capricornids are seen in the last week of July. The meteors are generally slow moving and often yellow in color.
Delta Aquarids
The Delta Aquarids are seen from mid-July to mid-August each year. The meteors are generally faint, and they appear from two radiants separated by about 10 degrees.
Iota Aquarids
The Iota Aquarids are seen in the first week of August. The meteors are often faint, and this shower is sparse in comparison with others.
Perseids
The Perseids are remnants of periodic Comet Swift-Tuttle. They are best seen in the second week of August. This a very rich shower with many swift bright meteors, persist trains, and some fireballs.
Orionids
The Orionids are associated with periodic Comet Halley and they are seen in late October. This is usually a prominent shower with swift meteors, many appearing in persistent trains.
Taurids
The Taurids are seen in the first week of November. They are associated with periodic Comet Encke. The meteors are usually slow moving, and they appear from two radiants separated by about 8 degrees.
Leonids
The Leonids are remnants of Comet Tempel-Tuttle of 1866. This shower is exceptional every 33 years, when the Earth passes through the densest region of cometary dust. In 1966 thousands of meteors per hour were seen. This should happen again in 1999.
Geminids
The Geminids are seen in the second week of December. This is one of the richest showers of the year. There are many bright meteors of medium speed, and an occasional fireball.
Ursids
The Ursids are visible a few days before Christmas. They are associated with debris from periodic Comet Tuttle. This is usually a weak shower with only a handful of meteors seen each hour.