Meteorites

Messengers from Space

verfasst von: Prof. Dr. F. Heide, Dr. F. Wlotzka

Verlag: Springer Berlin Heidelberg

Enthalten in: Professional Book Archive

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Meteorites - as well as shooting stars and meteors - result from a collision of a solid body from space with our Earth, but only meteorites are able to penetrate the Earth's protective shield, the atmosphere, and fall to the Earth's surface. Before the return of lunar samples, they were the only materials from beyond the Earth which we could take in hand and study.
This book gives a concise and up-to-date description of meteorites - fall phenomena, chemical and mineral composition, classification - as well as a discussion of their formation and origin, which also tells us the story of the formation of our Planetary System. The text is understandable for laymen and students, but can also be used as an introduction to the field for students and scientists.

Inhaltsverzeichnis

Frontmatter

Introduction

Abstract

Certainly every reader of this small book has already seen a shooting star. Out of the clear night sky a small point of light, no larger than its fixed-star neighbors, silently shoots across a segment of the heavens and disappears just as suddenly and as quietly as it appeared. “A star has fallen from heaven,” we say, and some take it as a good omen. Many readers, however, will have seen a rarer occurence in the night sky. Not just a point of light the size of a star, but a great ball accompanied by an eye-catching light display, radiant blue-white or reddish-yellow, silently traverses a great distance in the heavens and disappears below the horizon or suddenly extinguishes. These events are called Meteors. Still rarer and only witnessed by a few fortunate individuals, is a third, more dramatic phenomenon. The night suddenly becomes as bright as day. A large fireball leading a long, luminous trail is seen crossing the sky, and the sounds of whizzing and the clatter of thunder are heard. Lasting only a few spellbinding seconds, the display concludes with an explosive detonation.

F. Heide, F. Wlotzka

1. Fall Phenomena

Abstract

The first indications that a meteorite gives of its arrival on Earth are the light and sound phenomena that accompany its fall. The large distances over which these phenomena are visible and audible, and the resulting excitement produced, have induced people to promptly set down their observations in writing. As several hundred meteorite falls have been observed in the last century, the reports of eyewitnesses comprise voluminous literature.

F. Heide, F. Wlotzka

2. The Meteorites

Abstract

Meteorites range extraordinarily in size and weight. At the low end of the scale is cosmic dust, a term that designates particles smaller than 0.1 mm. These small particles are not melted by frictional heating during passage through the atmosphere. Due to their large surface to mass ratio, the generated heat is lost by radiation. There are also melted particles among these micrometeorites; they formed mainly by ablation from the molten surface of larger meteorites. The Earth accumulates about 10000 t of cosmic dust per year, but the problem for meteorite researchers is to distinguish it from the tremendous quantities of terrestrial dust. Two approaches to this problem have been found:

The capture of cosmic dust at high altitudes in the atmosphere;

The recovery of cosmic spherules from deep-sea sediments, or from Arctic or Antarctic ice.

F. Heide, F. Wlotzka

3. The Origin and Formation of Meteorites

Abstract

The materials from which meteorites were formed have had a complex history, which is presented schematically in Fig. 98. The beginning is nucleosynthesis, i.e., the production of the chemical elements by nuclear processes under conditions of very high temperatures and pressure in the interior of stars. All of the elements originated from hydrogen through the addition of protons, neutrons, and electrons. Over time, these materials were distributed throughout interstellar space. A localized cloud of higher density could have formed and through a process referred to as gravitational collapse produced the solar nebula. With further contraction and increase in density, the nebula evolved into the Sun and numerous small solid bodies (planetesimals). In a final stage, many of the planetesimals combined to form a smaller number of larger bodies, the planets. In such a body, referred to as the meteorite parent body, the history of a meteorite as an isolated piece of rock actually begins. Later, separated from its parent body, presumably by an impact, the meteoroid began its life as a small body in its own orbit around the Sun.

F. Heide, F. Wlotzka

4. Appendix

Abstract

As soon as the true nature of meteorites as extraterrestrial bodies was recognized, they were saved in collections. Several large collections were assembled already in the last century. These have been important for the study of meteorites, because the material is not readily available as terrestrial rocks are, and many meteorites are unique or of a rare type.

F. Heide, F. Wlotzka

Backmatter

Titel: Meteorites
verfasst von: Prof. Dr. F. Heide
Dr. F. Wlotzka
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-642-57786-4
Print ISBN: 978-3-540-58105-5
DOI: https://doi.org/10.1007/978-3-642-57786-4

Springer Professional

Über dieses Buch

Inhaltsverzeichnis

Frontmatter

Introduction

1. Fall Phenomena

2. The Meteorites

3. The Origin and Formation of Meteorites

4. Appendix

Backmatter