The luminosity does not depend on the actual size of the meteoric body. A fragment no larger than a pinhead can create a brilliant flash as it vanishes. A spectacular fireball that lights up the country over hundreds of miles may have a small body that burns up completely miles above the earth. A larger body can survive longer, so that it continues to flare for several seconds or more. The larger, long-lasting fireballs may explode into smaller fragments and cascades of sparks. In exploding, they can produce a luminous cloud of particles that remains visible for fifteen or twenty minutes and then peppers the ground with meteorites that fall like hail or buckshot. A giant fireball can deposit chunks of metal weighing a ton or more like those found in Mexico, or can leave a truly enormous body that penetrates the ground and carves out a great crater like those in Arizona and Texas.
To summarize: Huge fireballs of great brilliance are not new.
4. Sound. Some meteors produce noise; others do not. Most meteors silently vaporize high above the earth. When one does reach the ground, it may strike with no noise but the faint thud of its impact. Shooting through the air, it sometimes makes weak noises that have been described as rumbling, crackling, rustling, whistling, or hissing.
Meteors sometimes explode with one or more crashing detonations that rattle or even break windows. The noise has been described as like a heavy clap of thunder, the explosion of a volcano, or a whir as if a million bumblebees had been disturbed. The noise from the explosion of the Siberian meteor in 1908 was heard over a distance of 600 miles, and the shock registered as an earthquake in England.
Many meteors, like the Pennsylvania fireball of January 29, 1952, (AMS 2328) are completely silent. This blue-green object, so large that it showed a definite disk, was reported to the American Meteor Society by more than 400 witnesses from Maine to Virginia and from New York to Ohio; none of the observers heard any noise [[V-1], p. 264].
To summarize: Some meteors end with a bang, but most of them don’t even whimper.
5. Fragments. Most meteors burn up high in the atmosphere. A few, if they are large enough in size (at least ten to twenty pounds) and tough enough in structure, survive to reach the earth as stony or metallic fragments. Marked differences characterize the various meteor streams. The Taurids (maximum November 12) are relatively rigid structures, unusually tough, and show little tendency to break up in their flight. The many Taurid fireballs show that fairly large bodies have survived. The Geminids (maximum December 14) are of average strength but appear to be very dense, while the Draconids (October 10) are featherlike and fragile, with low density. Some of the most brilliant fireballs may be structures of ice and frozen gases which quickly vaporize on reaching the earth and hence leave no detectable fragments. The fiery object that struck Siberia in 1908 may have been such an “icy cometoid”; although it devastated an area of hundreds of square miles and uprooted or knocked down some eighty million trees, it apparently left no physical trace[[V-15]].
If some of the physical body does survive to reach the earth’s surface, finding it is still a problem. Recovery is rare even when the fall occurs in daylight over well-populated country and the flight path can be charted from the accounts of reliable witnesses. When the fall occurs at night, recovery is even rarer[V-5]. After dark, even experienced observers find it difficult to judge true directions and distances, and they may plot a place of fall that is many miles from the actual point of impact. Meteoriticists know that there is small chance of finding meteorites that fall at night except in regions where most of the land is under cultivation. In the fifty years between 1898 and 1948, of forty-eight recoveries from observed meteorite falls in the United States, only seven were made from falls occurring after 8 P.M.[[V-5]].
Recovery depends on many factors: the number of persons who saw the event, the accuracy of their estimates of distance and direction, the size of the meteorites, the patience of the searchers, the time and money available for the search, and, most important of all, just plain luck.
The Norton County fall of February 18, 1948, illustrates both the detective work and the luck required. At about 4:56 P.M. C.S.T. a brilliant detonating fireball soared over an area including Kansas, Nebraska, Colorado, Oklahoma, and Texas, and left a large white cloud that was visible for about an hour afterward. Newspapers publicized the phenomenon as a flying saucer and a few excited witnesses agreed. One man affirmed that shortly before the explosion the strange craft hovered over his yard at eye level, belching fire and showering sparks, then suddenly took off, climbing fast, and exploded.