Radiant

radiant: see meteor shower.

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radiant

1. emitted or propagated by or as radiation; radiated

2. Physics (of a physical quantity in photometry) evaluated by absolute energy measurements

3. a point or object that emits radiation, esp the part of a heater that gives out heat

4. Astronomy the point in space from which a meteor shower appears to emanate

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radiant [′rād·ē·ənt]

(astronomy)

A point on the celestial sphere through which pass the backward extensions of the trail of a meteor as observed at various locations, or the backward extensions of trails of a number of meteors traveling parallel to each other.

A point on the celestial sphere toward which the stars in a moving cluster appear to travel.

(physics)

Pertaining to motion of particles or radiation along radii from a common point or a small region.

A point, region, substance, or entity from which particles or radiations are emitted.

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Radiant 

the point on the celestial sphere that appears to be the source of the meteors observed when the earth encounters a swarm of meteoroids moving around the sun in a common orbit. Meteoroids belonging to the same swarm have almost exactly parallel trajectories in space. Consequently, if the paths of the meteors in the corresponding meteor shower are extended backward to the celestial sphere, they intersect in a small area of the sky because of the effects of perspective. The center of this area is the radiant.