Mavericks of the Solar System
from the book, "Our Fascinating Earth"
Mavericks of the Solar System
In certain regions of our planet strange glasslike pieces of rock have been found that have proved to be quite a puzzle to geologists. They are brown to green in color and are shaped like rods, spheres, disks, or buttons. They are generally smaller than two or three centimeters in diameter, with a few being over ten centimeters.
Usually found in clusters, they have been discovered in fewer than a dozen locations throughout the earth, mainly the Ivory Coast, Indochina, Australia, Texas, and the Czech Republic. Scientists refer to them as tektites. All tektites found in the same area are similar in structure and composition and have the same geologic age. All have the appearance of having once been partially molten. Perhaps one of the strangest things about them is that they have no geologic connection with the terrain in which they are found.
There are many theories as to the origin of tektites, but most known facts seem to point to an extraterrestrial origin. From which part of space they came and why they are so different from meteorites are more elusive questions.
Increased data derived from research indicate a possible lunar origin, a theory that is becoming more acceptable within the scientific community. Tektites appear to be fragments ejected into space from the moon as a result of heavy meteoric impact.
Given the low escape velocity from the moon (about one and a half miles per second) following impact by a large meteorite, fragments of the lunar surface can be expelled into space with sufficient velocity to avoid recapture by the moon. Some of these fragments can be thrown into trajectories that reach the earth, where they go into orbit. The ejected material is fused on impact by the meteorite but cools on its journey to earth. When its earth orbit decays, it fuses again because of friction with the atmosphere. The results are the small glasslike rock fragments of specialized shapes strewn in very specific localities.
If all this is true, then each large group of tektites would result from the formation of a large lunar crater by the impact of a specific meteorite. This would explain why tektites of one locale are the same age and of similar composition and why they differ from those of other regions.
Search on some Australian tektites shows they are remarkably similar in composition to those rocks found at the edge of the lunar crater Tycho, which was examined by the U.S. probe Surveyor 7 in the landing of January 1968. Extensive computer studies on possible trajectories of the Australian tektites indicate that they could have been formed by a shower of particles originating from Tycho.
Further evidence seems to support this. Since the Australian tektites are about 700,000 years old, it follows that the great lunar crater known as Tycho was created only 700,000 year ago by the impact of a gigantic meteorite.
Perhaps sometime in the near future the moon will again collide with a large meteorite and a new crater will be formed. When this happens, the earth may once more be hit by a shower of fiery lunar drops, and another field of space mavericks will be sown.