A meteor is a body of matter that enters the earth's atmosphere from outer space, appearing as a streak of light. It is commonly known as a shooting star. Meteors occur when meteoroids, small bodies orbiting our sun, enter the earth's atmosphere. Generally, meteoroids are between the size of a grain of sand and a large rock. Some meteoroids were formed at the same time as the solar system. Others come from the fragmentation of larger heavenly bodies, such as comets. Meteors can also have artificial origins. Man-made satellites sometimes fall from space, leaving bright trails.
In outer space, meteoroids move at a speed between 10 and 72 km per second. When they come into contact with the earth’s atmosphere, they burn at temperatures exceeding 2,500 degrees Kelvin. A meteor is formed when a meteoroid starts to disintegrate and becomes gaseous. The burning gases form a long, bright tail. Particularly bright meteors are called bolides, and create thunderous sounds audible for several minutes after they have been sighted. Meteoroids usually burn up completely during their descent through the atmosphere. When a meteor survives its descent and impacts the Earth, creating a crater, it is called a meteorite. Meteors occur frequently. Small meteoroids regularly enter the earth’s atmosphere. At certain times of the year meteors appear more often. This happens when the earth’s orbit takes it through fields of matter, often generated by the break-up of a comet. The effect, observed from earth, is known as a meteor shower.
One of the most regular meteor showers is the Perseids. Made up of matter left in space from the Swift-Tuttle comet, the Perseids are visible from almost everywhere in the northern hemisphere every July and August. Mankind has known about meteors since antiquity. In the past, meteors and comets were considered harbingers of important, and often bad events. In the Book of Revelation, a great meteor shower is one of the signs of the end of the world. Today, meteors have more positive connotations and in many countries people make a wish when they see one.