Meteor Stream


Also found in: Dictionary, Thesaurus.

meteor stream

[′mēd·ē·ər ‚strēm]
(astronomy)
A group of meteoric bodies with nearly identical orbits.

Meteor Stream

 

an aggregate of meteors visible in the atmosphere during the earth’s encounter with a meteor swarm —meteoroids moving in adjacent orbits and having a common origin. Sometimes the term “meteor stream” is also used to designate the meteor swarm itself that gives rise to the given meteor stream. The trajectories of all the meteors in a stream are almost parallel and appear to diverge approximately from a single point—the radiant of the meteor stream. Streams with a large number of meteors are named for the constellation in which the radiant lies or for the nearest bright star. Meteor streams are observed on approximately the same dates annually or once every several years. Several tens of nighttime meteor streams have been identified in the 19th and 20th centuries through visual observations. Radar observations of meteors have permitted the study of daytime streams as well. The orbits of several hundred meteor swarms have been determined by means of photographic and radar observations; most are similar to cometary orbits, primarily those of short-period comets. The orbits of several dozen meteor swarms lie close to the orbits of known comets; the connection between meteor swarms and known comets has been established in about 15 cases. (See Table 1.)

Meteor swarms are formed as a result of the disintegration of the nuclei of comets and initially move as a compact group occupying only a portion of the comet’s orbit. When they encounter the earth, the young compact swarms produce short-lived meteor streams with a very high number of meteors; such streams are called meteor showers. Under the action of gravitational perturbations by the planets, the Poynting-Robertson effect, and other factors, a meteor swarm gradually elongates along the orbit, expands, and finally disintegrates.

Table 1. Principal meteor streams
StreamPeriod of activityDate of maximumTable 1. Principal meteor streamsAssociated comet
QuadrantidsDec. 27-Jan. 7Jan. 3-4231+50 
LydridsApr. 15-26Apr. 21272+321861 I
η-AquaridsApr. 21 -May 12May 4336001910 II Halley
ArietidsMay 29-June 19June 745+23 
Southern δ-AquaridsJuly 21 -Aug. 15July 29339-17 
PerseidsJuly 25-Aug. 20Aug. 1246+581862 III Swift-Tuttle
DraconidsOct. 8-12Oct. 9-10268+601946 V Giacobini-Zinner
OrionidsOct. 14-26Oct. 2195+151910 II Halley
LeoaidsNov. 10-20Nov. 16152+221866 I
GeminidsDec. 1-17Dec. 13-14112+32 

Some currently observable meteor streams—for example, the Lyrids and the Perseids—have been known for several thousand years. Some meteor swarms that formerly produced active meteor showers—for example, the Andromedids and the Bootids—have moved out of the earth’s orbit because of planetary perturbations.

V. N. LEBEDINETS

References in periodicals archive ?
Past observations show that bright Geminids become more numerous some hours after rates have peaked, a result of particle-sorting in the meteor stream. This year, conditions are ideal as far as the Moon is concerned; New Moon is on December 16, so there will no interference from moonlight this year.
A meteor stream is like an enormous highway of moving particles, strung out along the entire elliptical path of the comet, and we become aware of only those particles that actually encounter our planet (a comparatively tiny target--a mere dot in space).
"It still means that there are pretty massive chunks in the meteor stream," Melosh comments.
As November approaches, amateur astronomers are eagerly awaiting this year's passage of the Earth through the Leonid meteor stream. After putting on a dazzling show last year (for which much of North America was clouded out!) the Leonid shower seems poised to produce a rich display of fainter meteors early on the morning of November 18th for some portion of the world.
The birth, life, and death of a meteor stream is reasonably well understood, at least in broad outline.
There's always a chance that you will observe something new and different, rare or unique, whether it be a new meteor stream, a brilliant fireball, or a long-enduring smoke train.
The source of a meteor stream was first identified in 1866 by the Italian astronomer Giovanni Schiaparelli (of Martian canali fame).
The project culminated with the publication of "Meteor Stream Activity" in the July (III) 1994 Astronomy & Astrophysics.
As suspected, the broad meteor stream has two peaks; since 1988 we have seen the emergence of a new, strong peak that precedes the traditional time of maximum.
The authors find that most of these detections coincide with 29 meteor streams during the study period.
Although parent to one of the better-known meteor streams, asteroid 3200 Phaethon remains a bit of a mystery object.
Both of these groups were discovered by citizen scientists who combined SOHO data with a number of Earth-crossing meteor streams. NASA and ESA hope that by understanding the evolution of this comet, scientists can learn more about the nature and origins of this complex family.