To the astronomer who specializes in the study of meteors the only peculiar aspect of the episode is that saucer publications list so few mysterious UFOs for that particular week when similar spectacular fireballs were almost a commonplace in the southeast states. On November 29 a meteor flew over Alabama at 5:30 P.M., and about two hours later another with a long trail soared over Florida. On November 30 at 5:00 P.M., a few hours after the fall at Sylacauga, another bright fireball flashed over Alabama. Shortly before midnight the same night a meteor flamed over North Carolina, so brilliant that its copper-green light illuminated the interior of cars on the highway; blue-green fire shot out above the treetops, changed to magnesium white, and then slowly faded. Detailed observations of all these appeared in the scientific journal Meteoritics[[V-1], p. 128].

Stones from Heaven

Until roughly a hundred and fifty years ago meteors and meteorites had the status of cosmic orphans, unacknowledged members of the astronomical family. Few persons doubted the existence of the fixed stars, the solar planets, comets, or even of “new stars” or novae, but they rejected a natural explanation for meteors and interpreted them as falling stars, flying dragons, or fountains of fire in the sky. Most astronomers as well as laymen laughed at the recurrent idea that “stones from heaven” could fall on the earth. Then in 1803 the French scientist J. B. Biot described an extraordinary rain of meteorites that fell at L’Aigle on April 26[[V-3]]; he convinced the French Academy of Sciences that the stones had indeed pelted from the sky during the great meteor display. Meteoritics is thus a relatively young science. Much remains to be learned about these cosmic visitors, but certain basic facts have been established[[V-4]].

Meteors enter the earth’s atmosphere continually, by day as well as by night, and they show great variety. Some are so brilliant that they are visible even in broad daylight. Some are so faint that even in darkness they can be seen only through a telescope. Others, still fainter, can be detected only by radar specially designed for this purpose. Because of the friction created when they penetrate the earth’s atmosphere, most meteors vaporize and vanish many miles above the ground. We see them as only bright streaks of light, quickly extinguished. If the meteoric body is large enough, has the right chemical constitution, and enters the atmosphere at a favorable angle and velocity, some of it may survive the journey and fall to the earth as a meteorite. A distinct odor sometimes accompanies the fall—the smell of sulphur, onions, or cyanide. About 40,000 tons of meteoritic material fall on the earth each day, most of it in the form of fine dust. The object may be a chunk of metal or stone the size of a pebble or a boulder, or it may be a mass weighing several tons, so enormous that it gouges out a crater at the place where it hits and comes to rest far beneath the earth’s surface. Some meteors, fortunately extremely rare, apparently can strike the earth and devastate a large area but, like the wind, leave behind no physical trace. According to present theory, members of a regular shower are probably remnants of comets, which have an icy structure, and the minute bits of frozen debris vaporize in a flash of light high in the atmosphere. Meteors that survive to reach the earth as meteorites are thought to be fragments of asteroids, or tiny planets. Meteorites vary so widely in their physical and chemical structure that they require a complex system of classification. Nevertheless the specialist can distinguish between a meteorite and earthly rocks and stones by laboratory tests[V-5].

Meteor Streams and Showers

Any clear night displays its quota of meteors. But at certain times, when the earth happens to collide with a stream of cosmic debris moving in an elliptical orbit, a shower of meteors takes place. (For a list of the major night meteor streams, see [Table I.]) Most meteor streams probably result from the breakup of comets; if the debris is distributed uniformly in the comet’s orbit, a meteor shower occurs each time the earth crosses the orbit. For example, the Perseids, fragments of Comet 1862 III, have reappeared every August for more than 1200 years, and the Leonids, debris of Comet Temple (1866 I), regularly return around the third week in November. Like the Taurids, another dependable stream, the Leonids are notable for their brilliant fireballs, which have deposited some of the largest meteorites ever found on the earth.

Some regular showers produce great numbers of meteors at intervals of several years. For nearly a millennium, A.D. 902 to 1866, a marked increase in the number of Leonids occurred every thirty-three years. The display in 1833 was one of the most spectacular in history, and witnesses said that the “stars were falling” as thick as snowflakes. Before the scheduled major shower of 1899, however, the main stream was deflected by passing close to the planet Jupiter and the periodic spectacle did not take place. Since then, the Leonids have been considered a “lost” stream, but some members of the shower have continued to appear each November. On November 16 and 17, 1961, they produced an unexpectedly awesome display with many brilliant fireballs.

TABLE I

MAJOR METEOR STREAMS

Name of streamDates of occurrenceDate of maximumParent cometRemarks
QuadrantidsJan. 1–4Jan. 3 Observed longer than 100 years.
LyridsApril 19–23April 211861 IObserved longer than 2500 years.
η AquaridsMay 2–5May 4Halley (1835 III)
δ AquaridsJuly 14-Aug. 19July 30
ι AquaridsJuly 16-Aug. 25July 30
PerseidsJuly 29-Aug. 17Aug. 121862 IIIObserved more than 1200 years.
α CapricornidsAug. 1–21Aug. 171948 n
CygnidsAug. 9–22Aug. 17
TauridsSep. 15-Dec. 2Nov. 12Encke (1957 c)
DraconidsOct. 9–10Oct. 10Giacobini-Zinner (1946 V)13-year period; great showers in 1933, 1946; none in 1959.
OrionidsOct. 18–26Oct. 22Halley (1835 III)
LeonidsNov. 14–20Nov. 17Temple-Tuttle (1866 I)Observed since A.D. 902.
GeminidsDec. 7–15Dec. 14
UrsidsDec. 17–24Dec. 22Temple (1939 X)