Causes of Meteor Explosion
Date: Winter 2012-2013
What causes a meteor to explode violently ? What is the chemical or thermal process?
As the meteor flies through the atmosphere at speeds far above the speed of sounds, the heat from friction with the atmosphere and the shock of a supersonic wave broke it apart explosively.
One thing is clear, there were no elements of a nuclear explosion. No radioactive components are involved. The references to atomic bombs used during World War II are just a means to describe the size of the explosion which is very common these days.
Here are two really clear and official reports:
“Friday afternoon, NASA scientists estimated the meteor was space rock about 50 feet (15 meters) and sparked a blast equivalent of a 300-kiloton explosion. The energy estimate was later increased to 470 kilotons….But late Friday, NASA revised its estimates on the size and power of the devastating meteor explosion. The meteor's size is now thought to be slightly larger about 55 feet (17 m) wide with the power of the blast estimate of about 500 kilotons, 30 kilotons higher than before, NASA officials said in a statement.”
Here is another descriptive article:
“The impact involved a 50-foot-wide (15-meter-wide), 7,000-ton asteroid that zoomed in from space at a velocity of 40,000 mph (18 kilometers per second), NASA officials said. They said the shock of atmospheric entry blasted the rock apart at a height of 12 to 15 miles (20 to 25 kilometers), releasing the energy equivalent of 300 to 500 kilotons of TNT. That's more than 10 times the energy released by the atom bombs that exploded over Japan at the end of World War II. In fact, NASA said its estimates were based on readings from infrasound sensors that were set up by the Comprehensive Test Ban Treaty Organization to detect nuclear blasts. The impact involved a 50-foot-wide (15-meter-wide), 7,000-ton asteroid that zoomed in from space at a velocity of 40,000 mph (18 kilometers per second), NASA officials said. They said the shock of atmospheric entry blasted the rock apart at a height of 12 to 15 miles (20 to 25 kilometers), releasing the energy equivalent of 300 to 500 kilotons of TNT. That's more than 10 times the energy released by the atom bombs that exploded over Japan at the end of World War II. In fact, NASA said its estimates were based on readings from infrasound sensors that were set up by the Comprehensive Test Ban Treaty Organization to detect nuclear blasts.”
You would do well to go to these URLs and review these articles for a more comprehensive understanding.
Good question! It is the thermal process. As the meteor enters the atmosphere it suddenly begins to heat up rapidly. As the speed plummets, the temperature rises and finally the object heats to incandescence an disintegrates. A big object, like the Russian one, will heat up and disintegrate explosively, emitting a shock wave that is heard as a tremendous crash. That shock wave is powerful enough to break windows and shake buildings.
David H. Levy
It is usually thermal. As a result of the thermal, chemical and physical processes become involved.
Meteorites are composed of rock and ice. As the meteor moves into Earth's atmosphere the friction of the air molecules causes the material to heat up and vaporize loosing material, called ablation.
The ablation does two things; it cools the meteorite by evaporation and it smooths the meteorite. Most meteorites on ground may only be hot enough to singe grass, they have been so cooled from evaporation. Ablated ice causes the clouds of vapor and the "fire" of the fireball is result of the ablated rocky parts.
If there is a small space within the rock that contains ice: the ice heats up to a vapor, causing great pressure - enough to explode.
Ablation of metal ions at high temperatures causes the electrons to leap to a higher energy level and decay creating colors characteristic of that metal. Sodium (Na) atoms give an orange-yellow light, iron (Fe) atoms a yellow light, magnesium (Mg) a blue-green light, ionized calcium (Ca+) atoms may add a violet hue, while molecules of atmospheric nitrogen (N2) and oxygen atoms (O) give a red light. The meteor color depends on whether the metal atom emissions or the air plasma emissions dominate.
Peter E. Hughes, Ph.D., Monadnock NH Radio Observatory, Milford, NH
Most meteors contain substances that in frozen in at the temperatures of space. Upon entering the Earth's atmosphere, the intense friction generates a lot of heat and this can very quickly convert the frozen substances to gases which then expands dramatically. This dramatic expansion is perceived as an explosion.
Greg (Roberto Gregorius)
Thanks for the questions. When a meteor enters Earth's atmosphere, it is traveling very fast (faster than the speed of sound). It encounters air resistance which slows the meteor and causes it to heat up. This heating process makes the meteor white-hot and therefore visible. The meteor cannot withstand the extreme temperatures and breaks up. There may be chemical reactions taking place at the same time. For instance, metals can be oxidized to form metal oxides.
I hope this helps. Please let me know if you have more questions.
When a solid body enters the atmosphere its temperature increases because of friction between the solid body and the surrounding air. The heat generated does several things. 1. It can cause volatiles in the solid body to increase in vapor pressure and cause a gaseous explosion. 2. If the mass, speed are large enough it can cause the solid components to also evaporate. This can cause the solid components to liquefy and then evaporate. This change in volume causes the meteor to explode. The details of these processes are very complicated, however.
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Update: December 2011