The faster the meteoroid travels just before hitting the atmosphere, the higher in the atmosphere the meteor trail occurs. The fainter is the meteor (the smaller the meteoroid mass), the shorter is the meteor length. The average meteor seen by the unaided eye starts with a meteoroid velocity of 18 mi/s (30 km/s) and leaves a luminous trail from 67 toĥ0 mi (110 to 80 km) high. The heights of appearance and disappearance of a meteor depend on meteoroid initial velocity, angle of entry with respect to the vertical, initial meteoroid mass, and meteoroid material strength. On average, an observer sees more meteors during the early morning hours as the Earth sweeps up objects in its path than in the early evening hours when meteor-producing objects must catch up with the Earth. As the Earth moves in its orbit, its velocity points toward that part of the sky (sometimes called the apex of meteor velocities) which is visible from local midnight through morning to local noon, and points away from that part of the sky which is visible from local noon through evening to local midnight. The spatial distribution of meteoroid orbits relative to the Sun, and the circumstances of their intersections with the moving Earth are responsible for pronounced variations in meteor rates.

Under normal, clear atmospheric conditions and dark skies (no moonlight or artificial lights), an observer will see an average of five meteors per hour. If the apparent brightness of a meteor exceeds that of the planet Venus as seen from Earth, it is called a fireball and when a bright meteor is seen to explode, it is called a bolide. Cosmic dust particles (with masses of micrograms) entering the atmosphere and leaving very brief, faint trails are called micrometeors, with the surviving pieces known as micrometeorites. The entering object is called a meteoroid and, if any of it survives atmospheric passage, the remainder is called a meteorite.

Meteor The luminous streak lasting seconds or fractions of a second and seen at night when a solid, natural body plunges into the Earth’s (or another planet’s) atmosphere.

Nova panasat ird 1110 manual