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Breaking the myths of meteorites

The term meteor comes from the Greek meteoron, meaning phenomenon in the sky. It is used to describe the streak of light produced as matter in the solar system falls into Earth’s atmosphere creating temporary incandescence resulting from atmospheric friction. This typically occurs at heights of 80 to 110 kilometers (50 to 68 miles) above Earth’s surface. The term is also used loosely with the word meteroid referring to the particle itself without relation to the phenomena it produces when entering the Earth’s atmosphere. A meteoroid is matter revolving around the sun or any object in interplanetary space that is too small to be called an asteroid or a comet. Even smaller particles are called micrometeoroids or cosmic dust grains, which includes any interstellar material that should happen to enter our solar system. A meteorite is a meteoroid that reaches the surface of the Earth without being completely vaporized.

Meteorites are an explosive phenomenon credited with such things as ending the age of dinosaurs, altering our planet, stimulating the beginning of life and daily threatening our very existence. Many of our myths about meteors come from a complete lack of understanding and sensationalized movies like Armageddon, Deep Impact, and Meteor.

The Myths:

1. Meteorites can be highly radioactive.

Actually meteorites are no more likely to be radioactive than ordinary terrestrial rocks.

2. Meteorites sometimes contain rare elements and exotic materials like Kryptonite.

Scientists report that no meteorite yet has been found to contain any element not occurring naturally on Earth.

3. Meteorites are rare and account for a very small amount of material reaching the earth.

Actually the Earth accumulates approximately 100 tons of extraterrestrial material every year. The current rate of fall for meteorites greater than 100g is approximately 27 per year. Meteorites as large as a basketball strike the Earth approximately once a month with nearly 75% of the impacts landing in water.

4. There are just a few known impact sites in the world.

The latest scientific count has 174 documented craters (impact structures) and the list is growing as detection technology and awareness continues to spread quickly worldwide. Other research groups have documented 543 suspected Earth impact craters.

This map documents the known and suspected Earth impacts. What is particularly amazing is that if nearly 75% of all meteorites land in the water the count would be many times higher than what is primarily evidenced by land impacts.

5. No one is looking for a Doomsday asteroid.

A large and growing network of scientists are tracking an astoundingly large list of dangerous asteroids. NASA maintains a current list of potentially hazardous asteroids. Consulting the list reveals hundreds of near earth asteroids being closely monitored by scientists the world over.

6. The odds of a significantly sized asteroid striking the Earth are too small to calculate.

Actually scientists place the odds of a significant, life altering, meteorite event at 1 in 40 by 2029. More specifically scientists expect the recently detected asteroid Apophis MN4 2004 to have a surprisingly high impact probability on April 13, 2029 with a near Earth pass as close as 3,380km.

Other close calls include asteroid 1989 FC with a diameter about 0.3 miles and a kinetic energy of over 1,000 one-megaton hydrogen bombs, which on March 23, 1989 passed within 430,000 miles of the Earth. This asteroid was not discovered until it had already passed its point of closest approach, and only after calculating backwards its orbital path. Since then several other celestial bodies of similar sizes have been measured as coming within 62,000 miles of Earth.

7. Meteorites are meaningless except as threats to our existence.

Actually, besides the known effect they have had on life and dinosaurs, meteorites have revealed or contributed through impact a tremendous volume of natural resources to our planet. Extraterrestrial objects colliding with Earth can cause dramatic changes to the planet and affect the course of evolution.

An impact in the region around Popigai, Siberia created a 60-mile-diameter crater and industrial-grade diamonds. When the diamonds were discovered in modern times, the area was closed to outsiders in the event the diamonds might prove valuable some day.

Another impact site called the Alamo Breccia, a fragmented carbonate rock now found in the mountains about 100 miles north of Las Vegas, Nev., is composed of pieces of lagoon sediments and fossils, typical of an ancient shallow ocean. The Breccia contains shocked quartz from the impact, carbonate spherules from the vapor cloud that was created, and iridium from the projectile itself.

The historical impacts to the terrain have revealed or contributed to mines, oil reserves, natural springs, silica, iron in places they would not ordinarily be revealed. Much more is still being learned about the wide variety of impact sites and the resulting wide range of mineral resources not ordinarily found in these locations.

Another such example is the Carswell crater of Saskatchewan which benefited from a meteor impact in the Cluff Lake area, where the impact created an uplift of the Athabascan sandstone revealing a number of large unconformity-type uranium deposits.

The above sea level portion of the rim of a huge meteorite impact crater known as the Chicxulub impact crater, located in Mexico has been studied amongst others by Glamis Gold.

The Vredefort crater of South Africa well-known for its gold-uranium deposits is intensively mined by different companies.

Lately, Great Australian Resources started investigating the South African Morokweng impact crater, where drilling intercepted high-grade nickel sulphide mineralization.

posted by: kyawoo at 19:46 | link | comments (1) |
meteorites

Comments:

#1  25 April 2006 - 09:12

 

Hello ..
You 've got good posts in here.Keep up the good job,buddy ! Cya around ..

Anonymous

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