Importance
(1) Origin of Earth/Solar System (lithosphere, hydrosphere + atmosphere) - 4.6 billion years ago. Earth (+ solar system) formed by collisions of many meteorites (pieces of rock + metal, photo) + comets (dirty ice balls, photo). Scars from those ancient collisions (craters = bowl-shaped depressions produced from meteorite collision) are still clearly visible on Moon, but far fewer impact craters on Earth. Why?
See meteorite impact craters on Moon (photo #1, #2) and on Earth (photo #1, #2, #3).
(2) Role in evolution + origin (?) of life - meteorite impacts caused several mass extinctions (global dyings) during Earth history + perhaps even origin of life because some meteorites (carbonaceous chondrites) contain protein-related amino acids, building blocks of life
(3) Economic Resource - certain metallic ore deposits
(4) Potentially catastrophic future natural disaster - Meteorite impacts can potentially produce most catastrophic consequences of any natural disaster, potential to cause mass extinction of many organisms including human beings
Introduction
Meteorites have played important role in human history, e.g., Islam religion has sacred rock in Mecca, Saudi Arabia, thought to be iron meteorite.
On June 30, 1908, mysterious explosion occurred in Tunguska region, central Siberia. Massive fireball streaked across sky, causing incredible blast of heat + exploded ~8 km above ground; sound from explosion heard up to 1,000 km away. No deaths only because closest human was tens of km away; trees in area >1,000 km2 were destroyed + charred on one side; no crater. Explanation = 30 - 50 m comet (or stony meteorite) exploded above Earth's surface; comets (weak bodies) can easily disintegrate in Earth's atmosphere without striking Earth, producing no crater.
