The following definitions are those used by the IMO in their Handbook for Visual Meteor Observers:
ABLATION - removal of material by attrition, e.g., by passage through the atmosphere.
ABSOLUTE MAGNITUDE - the stellar magnitude any meteor would have if placed in the observer's zenith at a height of 100 km.
ALTITUDE - the angular distance of a celestial body above or below the horizon, measured along the great circle passing through the body and the zenith. Altitude is 90 degrees minus zenith distance.
ASTEROID - one of a number of objects ranging in size from sub-kilometer to about 1,000 kilometers, most of which lie between the orbits of Mars and Jupiter; also called "minor planets".
AZIMUTH - the angular distance measured clockwise along the horizon from a specified reference point (usually north) to the intersection with the great circle drawn from the zenith through a body on the celestial sphere.
BROWNLEE PARTICLES - interplanetary dust particle (IDP), also known as a micrometeoroid or, after entry into the Earth's atmosphere, a micrometeorite.
DECLINATION - angular distance north or south of the celestial equator.
ECLIPTIC - plane of the Earth's orbit.
ESCAPE VELOCITY - the velocity required to escape entirely from the gravitational field of an orbit; also the minimum impact velocity for any body arriving from a very great distance.
FALL - a meteorite that was seen to fall. Such meteorites are usually recovered soon after the fall and are relatively free of terrestrial contamination and weathering effects.
FIND - a meteorite that was not seen to fall but was found and recognized subsequently.
FIREBALL - a bright meteor. Several definitions have been used by various authors. In the IMO's Fireball Data Center (FIDAC) all meteors of at least -3.0 magnitude are stored as fireballs.
GEOCENTRIC - Earth-centered.
HELIOCENTRIC - Sun-centered.
MAGNITUDE - an arbitrary number, measured on a logarithmic scale, used to indicate the brightness of an object. The brighter the star, the lower the numerical value of the magnitude and very bright objects have negative magnitudes.
METEOR- the light phenomenon produced by a meteoroid experiencing frictional heating when entering a planetary atmosphere; also used for the glowing meteoroid itself. If particularly bright, it is described as a fireball.
METEORIC - the adjective form pertaining to meteor or meteoroid.
METEORITE - a natural object of extraterrestrial origin that survives passage through the atmosphere.
METEOROID - a natural small solid object in an independent orbit in the Solar System.
METEOROID STREAM - stream of solid particles released from a parent body (comet or asteroid). Various ejection directions and velocities for individual meteoroids cause the width of a stream and the gradual distribution of meteoroids over the entire average orbit.
METEOR SHOWER - many meteors appearing to radiate from a common point in the sky caused by the collision of the Earth with a swarm of meteoroids.
MINOR PLANET - asteroid.
PARENT BODY - a comet or asteroid which released meteoroids (as well as dust and gas) when passing the inner Solar System and which may form a meteoroid stream.
PERSISTENT TRAIN - remaining glow due to ionization in the upper atmosphere after the passage of a meteoroid. The intensity and duration depends on the meteoroid's atmospheric entry velocity, its size, and its composition.
RADIANT - the point where the backward prolongation of the meteor trajectory intersect the celestial sphere, or the backwards prolongation of the apparent trails of a given meteor as seen by observers at different locations.
RADIANT DRIFT - shift of a radiant position due to the Earth's passage through the meteoroid stream.
RIGHT ASCENSION - angular distance east of the vernal equinox, as measured on the celestial equator.
SOLAR LONGITUDE - angular distance along the Earth's orbit, measured from the vernal equinox. It gives the position of the Earth at its orbit and hence is more appropriate for designating a meteor shower's maximum than the date.
SPORADIC METEOR - a meteor which cannot be associated with any known or detectable meteor shower.
TRAJECTORY - path of a meteor in the Earth's atmosphere.
UNIVERSAL TIME - the local mean time of the prime meridian. It is the same as Greenwich mean time, counted from 0 hour beginning at Greenwich mean midnight.
ZENITH ATTRACTION - the effect of the Earth's gravity on a meteoric body increasing the velocity and moving the radiant toward the zenith.
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