Introduction

Perhaps you have been out on a clear moonless night and saw a bright streak of light in the sky and wondered what it was. This is an account of a fantastic event, what it was and what it could end up as.

Many people today have no background on meteors and meteorites. This may help explain what they are, where they came from, where they are going and their origin.

Meteor Crater

The word “Meteor” is derived from the Greek for something in the air, and in its original sense referred to various phenomena that appear in the earth’s atmosphere. In today’s usage, however, the term applies strictly to the visible light that is seen when an object from space encounters the earth’s atmosphere at high velocity. “Fainter meteors are frequently termed ‘Shooting Stars’ or ‘Falling Stars’ in popular terminology, whereas very bright meteors are referred to as ‘Fireballs’ or ‘Bolide’. The fireball is one of the most spectacular phenomena.”1 The scientific study of meteors is a relatively new field of investigation.

On a clear moonless night, an observer can see from five to ten meteors per hour if they watch the sky continuously. The majority of them are quite faint, and the number seen from the center of a city will be much smaller. On the average, more meteors per hour are seen during the second half of the night, since at this time the observer is on the front side of the earth in its journey around the sun. The individual observer can see only the meteors in a two to three hundred mile radius of his position. “The actual total of visible meteors encountered daily by the earth is several hundred million, and many times this number enter the atmosphere but are too faint to be seen by the naked eye.”2

“The daily mass accumulated by the earth in the form of meteors and meteoritic dust is possibly several thousand tons, much the greater part of this being accounted for by the tiny particles that never become visible.”3 This may seem to be a lot, but it isn’t compared to the earth’s mass.

Attempts to estimate the speed of a meteor have been very unsuccessful by the naked eye. There are two mechanical methods for measuring the velocity of a meteor. “The first of these is photographic and consists of equipping a meteor camera with a rotating shutter that covers and uncovers the lens at a fixed rate, usually somewhere between 10 and 60 times per second.”4 “The second method for measuring velocity is a radio technique.”5

“Most meteors travel at about 10 to 40 miles per second when they enter our atmosphere.”6” The majority have velocities in the range either near 20 miles per second or 35 miles per second.”7 These two speeds of meteors correspond respectively to meteors which overtake our earth and those which meet the earth. “The fact that meteoritic particles strike the earth at speeds below this critical limit of 45 miles per second is a fairly good indication that, in general, they are members of the sun’s family and are moving in orbits somewhat similar to those of planets or comets.”8

“At approximately 60 or 70 miles above our head the rock started to glow a bright white color.”9 The faster meteors appear closer to 70 miles high. The slower ones will appear closer to 50 miles up. “The fainter meteors disappear five to ten miles after they had become visible.”10 “The higher meteors remain visible down to heights of 30 to 40 miles high above the earth’s surface and in some cases may even be lower.”11 Normally the meteors are brighter during the second half of their life in our atmosphere.

If the exact speed and direction of a meteor can be determined, it is easy to determine its orbit around the sun. For the great majority of meteors seen by the naked eye have orbits that are highly elongated ellipses that lie near the sun at one end and extends out to or beyond the larger explanetory orbits at the other. This is the type of orbit that a comet has and it is believed that these meteors and most others have had closely connected origins. “In fact many meteors are found to be moving along the orbit of certain well-known comets, and these can be thought of as cometary debris.”12

On certain nights of the year numerous meteors are seen to be traveling along parallel paths. This phenomenon is called a “Meteor Shower”, and on these occasions the earth cuts through a meteor orbit or meteor stream. As the earth moves through them, it sweeps up large numbers, which then appear as meteors in our atmosphere. The shower is named by the point next to the constellation or in a constellation from which the meteors look as if they are coming from. An example is the “Geminid” meteors which paths seem to radiate from Gemini.

Meteoritic particles do not slow down very much during the time that they are luminous, but the particle loses mass continuously. “Sometimes sudden bursts or flares are seen, and this indicates the rapid break-up or crumbling of portions of the material.”13 This phenomenon is more common in the case of the brighter objects.

“Bright meteors frequently leave a fain residual luminosity near the position of the maximum light.”14 This is know as the “persistent train” of the meteor. It rapidly fades, and its shape alters from an initial straight line to a diffuse and wavy trace in the sky, much like a smoke trail. There is still much to learn concerning the physical processes that produce the self-luminous meteor trains.

A meteoritic particle enters the earth’s atmosphere at a high velocity. These meteors are hunks of stone or iron that enter our atmosphere and burn up by the friction of our atmosphere. These meteors are traveling at, perhaps, 20 to 30 miles a second. At approximately 60 to 70 miles above our head the air is thick enough to offer serious friction and make it glow a bright white. “When the meteor gets about 20 miles form the earth it has entirely disappeared by the friction and the hot heat of it flying through the atmosphere.”15

Meteorites were once a mystery to man. Man thought they came from other worlds and were sent by other people. Modern science has shown that these are iron rocks that fall into the earth’s atmosphere. “The fall of a meteorite was reported by the Roman scholars, Plutarch and Pliny, in 467 B.C.”17 “A shower of about 2,000 meteorites fell in Normandy, France on April 26, 1803.”18 Generally,, meteorites have caused little damaged to man. “A few years ago a small meteorite which fell in Illinois went through the roof of a garage and through the automobile inside.”19 No one was hurt. Many years ago a meteorite flattened a forest in Siberia. There are also many pits in the western part of the United States. I have seen on of the most famous meteors called “Meteor Crater” in Arizona. I visited this meteor in the Summer of 1966.

“Meteor Crater - the world’s first proven meteorite crater - is 4,150 feet from rim to rim, three miles in circumference and 570 feet deep. Such man-made wonders as the Washington Monument and the massive Great Pyramid of Cheops of Egypt are dwarfed by its giant dimensions.

The meteoritic mass from outer spaced that gouged out Meteor Crater - possible a wondering asteroid or the head of a disintegrated comet - struck the earth here with a force of a multimegaton hydrogen bomb, splashing nearly half a billion tons of rock from the crater and probably destroying all plant and animal life within a 100 mile area.

If early man lived in Norther Arizona at the time, and it is very possible he did, he probably watched in fear and awe the blinding flash and earth shaking explosion of the meteorite’s impact here. Recent dating tests using the new radioactive carbon isotope method indicate that the meteorite, weighing perhaps more that a million or more tons, struck here at least 12,000 years ago - a time when great glaciers still covered much of the norther part of our continent. More recently, Meteor Crater has been a familiar landmark to both ancient and modern Indian tribes for more than 1,500 years and is linked with their tribal customs and legends.

Meteor Crater, also know as Barringer Crater, was first discovered by white men in 1871 and for many years was thought to have been of volcanic origin. However, in 1903, a Philadelphia mining engineer, Daniel Moreau Barringer, acquired the crater and initiated a series of intensive scientific studies that shortly before his death in 1929 led to full scientific recognition of the fact that the crater was actually the result of the impact of a huge meteoritic mass from outer space. Thus, in turn, spurred scientific investigation at the crater and, and through identification of its peculiar features, such as shatter cones, and rare minerals formed by the impact, coesite and stishovite, led to the discover of a number of other craters of meteoritic origin in various parts of the world. These craters, mostly less conspicuous because many of their distinctive features have disappeared through erosion, range in size from the Vredevert Ring in South Africa, 130 miles in diameter and 250 million years old, to the Sikhote-Alin group of 200 craters and pits, formed by a meteoritic shower in Siberia in 1947.

American astronauts, some of whom will walk the surface of the moon someday, use Meteor Crater and other unique Northern Arizona geological features as an important training are. This stems from meteor Crater’s uniqueness as the only geological formation on earth that closely approximates in size and structure the great craters that scar the bleak, airless surface of the moon. Scientists have generally accepted the idea that the lunar craters were also the result of the impact of thousands of meteorites over the 4.5 billion years the moon is estimated to have orbited the earth. The astronauts have already made intensive studies of Meteor Crater so that they will be better prepared to recognize and cope with similar geologic features they are expected to find on the moon.

Meteor Crater has aided science in many other ways. Geologists from all over the world have visited the crater and studied its unique features. Members of the U.S. Geological Survey’s new space age Branch of Astrology, head-quartered in nearby Flagstaff, have learned much new knowledge of the earth itself and of meteorites and lunar geology through researches they are conducting at Meteor Crater.

Meteor Crater’s museum is open from sunrise to sunset 365 days a year. To further the visitor’s understanding of this natural wonder, a brief explanation is given in the museum, and on its veranda overlooking Meteor Crater, of the crater and its history. Diagrams, and a large collection of meteorites and minerals are displayed in the museum, which also features and outstanding exhibit of fluorescent minerals housed in the ultraviolet-lighted Chameleon Room. Samples of these minerals, including fragments of meteorites, may be purchased in the museum’s Rock Shop, one of the most completer in the American Southwest.

A second brief lecture on the crater and on the unique and fascinating are surrounding Meteor Crater is given at the summit of Moon Mountain, the highest point on the crater’s jagged blast crater rim. A high-power telescope located on this summit, provides a superlative view of the surrounding points of interest - the many-hued Painted Desert, the towering, often snow-hued San Francisco Peaks, the remote Hopi Mesas and many other unusual sights.

A trail winds around the three-mile rim of Meteor Crater, a brief but pleasant hike, and trails also lead from the museum to the bottom of the crater, a some-what strenuous walk. In connection with the museum, a lounge are and gift shop offers Indian arts and crafts, including handmade pottery, jewelry and other artifacts, as well as a complete selection of souvenir and gift items and camera supplies. An automated snack bar provides sandwiches, soft drinks, coffee, beer and ice cream.

The great Meteor Crater of Arizona, one of the natural wonders of the world, is almost centrally located amid Northern Arizona’s other great scenic wonders - the mighty Grand Canyon to the northwest, the fantastic Petrified Forest/Painted Desert National Park to the northeast. In addition, no less than 13 national monuments, marking extensive prehistoric Indian ruins, are within easy driving distance of Meteor Crater.

The crater itself is on the southern edge of the sprawling Navajo and Hopi Indian reservations. Include a stop at Meteor Crater when planning to visit this great natural wonderland.

Meteor Crater is easily reached by an all-weather, paved access road from U.S. Highway 66 between Flagstaff and Winslow, Arizona.

Fourteen meteorite craters, this being the largest, have been proven to date by the finding of meteorites in the surrounding areas. All were made within recent geologic times. However, there are some 30,000 craters on the 60% of the moon’s surface which can we can see from Earth and it is believed that most of them were made by meteorites. Since the moon has no atmosphere it has no forces to cause erosion; so it has long been realized that the earth also must have been struck by many many meteorites, some of them huge, but that erosion has destroyed the evidence. The recent finding on the rim of this crater of high-pressure form of silica seems to have proved this theory. This material, coesite, had been made in the laboratory and was known to require pressure of about 300,000 pounds per square inch for its formation, but it had never been found in nature. It has since been found in connection with other geological features, some at least 500 million years old. Most of these are so eroded as to be unrecognizable as craters, so they have been given the name of astroblemes, or star wounds.

Meteorites from nearly sixteen hundred falls have been classified to date. They are divided into 3 major classifications: stony, stony-iron and nickle-iron meteorites. Those that fell here are in the nickle-iron classification and analyze about 93%iron, 7% nickle, with traces of many other elements. Studies of some of the trace elements found in them have led to the conclusion that our earth is about 5½ billion years old. Tiny diamonds and natural carborundum, also found in them, testify to the great heat and pressures generated here when the meteorite struck.”20

I hope that this paper has taken the wonder out of what that streak of light in the sky was and replaced it with scientific fact. When you significant other says that they will make a wish because they saw a falling star, you can now tell them that stars don’t fall and that steak of light was actually a meteor.

Just a side note here, this paper was written in 1967 for a highschool report. Some of the text is outdated as to the moon mission, but the fact still remain solid.

Photos by NASA

1. Shores, Louis, Ph.D. Colliers Encyclopedia Vol. 16 (Great Britian, Crowell-Collier, 1960) P 35
2. Ibid P 35
3. Ibid P 35
4. Ibid P 35
5. Ibid P 35
6.Thomson, J. Arthur The Outline Of Science Vol. 11 (New York, G. C. Putnam’s Sons, 1922) P 35
7. Op Cit Shores, Louis Ph.D. Vol. 16 P 36
8. Ibid P 36
9. Op Cit Thomson, J. Arthur The Outline Of Science Vol. 11 P 35
10. Op Cit Shores Collier’s Encylopedia Vol. 16 P 35
11. Ibid P 36
12. Ibid P 36
13. Ibid P 37
14. Ibid P 37
15. Op Cit Thomson, J. Arthur The Outline Of Science Vol. 11 P 35
16. Op Cit Editors of Britanica Junior Vol. 10 P 158
17. Ibid P 159
18. Ibid P 159
19. Ibid P 159
20. Meteor Brochure and Lecture