Meteor

respectively, a glowing streak in the sky (meteor) and its cause, which is a relatively small stony or metallic natural object from space (meteoroid) that enters Earth’s atmosphere and heats to incandescence. In modern usage the term meteoroid, rather than being restricted to objects entering Earth’s atmosphere, is applied to any small object in orbit around the Sun having the same nature as those that result in meteors.

...three aspects of knowledge. Hordubal (1933) contrasts an inarticulate man’s awareness of the causes of his actions with the world’s incomprehension; Povětroň (1934; Meteor) illustrates the subjective causes of objective judgments; and Obyčejný život (1934; An Ordinary Life) explores the complex layers of personality...

...Cup yacht races. In 1925–27 a series of scientific voyages by the research vessel Meteor established Germany as a leader in marine research. Operating in the waters of the South Atlantic, the Meteor traversed the basin 14 times, mapping the...

temporary rise in the rate of meteor sightings, caused by the entry into Earth’s atmosphere of a number of meteoroids (see meteor and meteoroid) at approximately the same place in the sky and the same time of year, traveling in parallel paths and apparently having a common origin. Most meteor showers are known or believed to be associated with active or defunct comets; they represent Earth’s passage through the orbits of these comets and its collision with the streams of debris (typically of sand-grain to pebble size) that have been left behind. The showers return annually, but, because the densities of meteoroids in the streams (commonly called meteor streams) are not uniform, the intensities of the showers can vary considerably from year to year.

major meteor shower occurring in the Northern Hemisphere from July 23 through August 23. The date of maximum visibility, however, occurs only on August 12. The comet associated with this shower is named 1862 III. At its maximum, the number of meteors that can be seen per hour is about 68. During a shower, meteors appear to stream outward from a point in the sky called the radiant, which marks the point of intersection of the Earth's orbit with the orbit of the meteoroids. A radiant is usually a constellation. The radiant associated with the Perseids is the constellation Perseus. The Perseids were named after the mythological Greek hero Perseus. It is believed that the Perseids have been known since ancient times.

A flaming streak flashes across the night sky and disappears. On rare occasions the flash of light plunges toward Earth, producing a boom like the thundering of guns and causing a great explosion when it lands. When ancient peoples witnessed such displays, they believed they were seeing a star fall from the sky, and so they called the object a shooting star or a falling star.

A meteoroid moving through outer space may pass close enough to the Earth to be trapped by the planet's gravitational field. If this happens, the meteoroid is drawn into the atmosphere and toward the Earth's surface by the force of gravity.

As the Earth travels in its orbit around the sun, it continually encounters meteoroids head-on. On a clear, dark night an observer may see ten or more meteors per hour. Sometimes an unusually large number of small meteors can be seen in rapid succession—perhaps more than 50 per hour. Such a display is called a meteor shower and occurs when the Earth passes through a swarm of meteoroids. Because of their small size, these meteors generally burn up in the upper atmosphere and never reach the ground.

Sometimes one can see a flash of light streak across the night sky and disappear. Although this is commonly called a shooting star, real stars do not shoot through the sky any more than the sun does. Many small chunks of stone, metal, or other materials orbit the sun. Sometimes they enter Earth's atmosphere, and the friction generated by their great speed causes them to burn up. The fragments may either vaporize before traveling far or actually hit the ground.

A meteor is the streak of light in the sky that results when a rock or other body burns up as it falls through the atmosphere. Meteors are also called shooting stars or falling stars. The object that is falling is called a meteoroid. If the object survives its fall and reaches the surface of the Earth, it is called a meteorite.

At times, people can see thousands of meteors per hour. These meteor showers often occur as the Earth passes through the orbit of a comet. They are caused by bits of rock and ice left behind by the comet. Each year in July and August the Earth crosses the path of the Swift-Tuttle comet. The resulting meteor shower lasts about five days. It is called the Perseid shower because it occurs in the sky near the constellation, or group of stars, known as Perseus.

The atmosphere of the Earth is the layer of gas that surrounds the planet. It is often called air. The gas molecules that make up the atmosphere are held close to the Earth by gravity. The atmosphere protects the Earth's inhabitants from dangers such as radiation from the sun and meteor particles. Other planets, and some of their larger moons, also have atmospheres.

The asteroids are millions of rocky fragments that orbit the sun, for the most part in a loose band between Mars and Jupiter. They are believed to be debris left over from collisions between other bodies in the solar system. The largest asteroids are hundreds of miles in diameter, but most are much smaller. Occasionally, small asteroids or other pieces of solar system debris, including interplanetary space dust called micrometeorites, fall into the Earth's atmosphere and become glowing meteors.

Planets are relatively large natural bodies that orbit around stars. Although there may be many planets in the universe, the most well-known are the ones that orbit around Earth's sun. The collection of the sun and these planets is known as the solar system.