Miracle Planet: Asteroid Collision
Collision of a Large Meteorite with the Earth



 
Miracle Planet: Asteroid Collision
Collision of a Large Meteorite with the Earth


What would happen if a 500km sized (300 mile) asteroid impacted planet earth? The following computer simulation provides some details to what this impact may look like. This is not a doomsday video, this is a video demonstrating what an impact would look like. The last known impact this size that has occurred on planet earth was over 4 billion years ago.



An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet.

Throughout recorded history, hundreds of minor impact events (and exploding bolides) have been reported, with some occurrences causing deaths, injuries, property damage or other significant localized consequences.

Impact events have been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream.


An impact event is commonly seen as a scenario that would bring about the end of civilization. In 2000, Discover Magazine published a list of 20 possible sudden doomsday scenarios with impact event listed as the No. 1 most likely to occur.

Until the 1980s this idea was not taken seriously, but all that changed after the discovery of the Chicxulub Crater which was further reinforced by witness to the Comet Shoemaker-Levy 9 event.


Comet Shoemaker-Levy 9 (formally designated D/1993 F2, nicknamed String of Pearls for its appearance) was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of solar system objects.


The impactor's estimated size was about 10 km (6 mi) in diameter and is estimated to have released 4×1023 joules of energy, equivalent to 100,000,000 megatons of TNT on impact.

By contrast, the most powerful man-made explosive device ever detonated, the Tsar Bomba, had a yield of only 50 megatons, making the Chicxulub impact 2 million times more powerful.

Even the largest known explosive volcanic eruption, which released approximately 1021 joules and created La Garita Caldera, was substantially less powerful than the Chicxulub impact.

The impact would have caused some of the largest megatsunamis in Earth's history, reaching thousands of feet high. A cloud of super-heated dust, ash and steam would have spread from the crater, as the impactor burrowed underground in less than a second.


Excavated material along with pieces of the impactor, ejected out of the atmosphere by the blast, would have been heated to incandescence upon re-entry, broiling the Earth's surface and possibly igniting global wildfires; meanwhile, colossal shock waves spawned global earthquakes and volcanic eruptions.

 
The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named.

The crater is more than 180 km (110 mi) in diameter, making the feature one of the largest confirmed impact structures on Earth; the impacting bolide that formed the crater was at least 10 km (6 miles) in diameter.


In March 2010, following extensive analysis of the available evidence covering 20 years' worth of data concluded that the impact at Chicxulub triggered the mass extinctions during K-T boundary including those of the dinosaurs.





Chicxulub Impact Visualization

A visualization of the immediate and long-term environmental effects of the impact event which marked the end of the Cretaceous period, circa 65 mya.

If such an impact were to occur today, the best strategy for immediate survival would be to be in a different hemisphere when it happened.

The kinetic energy of a six-mile-wide rock piling into the earth at 50,000 mph must be conserved, and in order to do this much of this energy is converted to thermal energy - enough to cause third-degree burns from seven hundred and fifty miles away, and to light you on fire if you are much closer.

Little to nothing would survive within six hundred miles of the impact zone - note the "scorched earth" appearance of the North American continent at KT + 2 weeks.

Other immediate effects include a major earthquake, an airblast capable of leveling forests and buildings, semi-molten ejecta raining from the sky and sparking global wildfires and, once the shockwave reaches the antipodal point of the Earth, massive volcanic eruptions which can last for many thousands of years (such as those that formed the Siberian Traps).

A modern theory states that not one, but several impacts ushered forth the mass extinction to follow, including the impacts which created the Silverpit Crater in the English Channel, and Boltysh Crater in the Ukraine; though neither were as large or devastating as Chicxulub, they are possibly the result of an impact similar to comet Shoemaker-Levy 9 on Jupiter.



The emission of dust and particles could have covered the entire surface of the Earth for several years, possibly a decade, creating a harsh environment for living things to survive.

The shock production of carbon dioxide caused by the destruction of carbonate rocks would have led to a sudden greenhouse effect.


Over a longer period of time, sunlight would have been blocked from reaching the surface of the earth by the dust particles in the atmosphere, cooling the surface dramatically. Photosynthesis by plants would also have been interrupted, affecting the entire food chain.

There was however a quick recovery of plants only few months after the impacts. In February 2008, a team of researchers led by Sean Gulick at the University of Texas at Austin’s Jackson School of Geosciences used seismic images of the crater to determine that the impactor landed in deeper water than was previously assumed.

They argued that this would have resulted in increased sulfate aerosols in the atmosphere. According to the press release, that “could have made the impact deadlier in two ways: by altering climate (sulfate aerosols in the upper atmosphere can have a cooling effect) and by generating acid rain (water vapor can help to flush the lower atmosphere of sulfate aerosols, causing acid rain).”



Meteorite Collision with Earth
A simulation of what a meteorite collision with Earth might look like.

Small objects frequently collide with the Earth. There is an inverse relationship between the size of the object and the frequency that such objects hit the earth.

Asteroids with a 1 km (0.62 miles) diameter strike the Earth every 500,000 years on average.

Large collisions – with 5 km (3 miles) objects – happen approximately once every ten million years.


The last known impact of an object of 10 km (6 miles) or more in diameter was at the Cretaceous-Tertiary extinction event 65 million years ago. Asteroids with diameters of 5 to 10 m (16 to 33 ft) enter the Earth's atmosphere approximately once per year, with as much energy as Little Boy, the atomic bomb dropped on Hiroshima, approximately 15 kilotonnes of TNT.

These ordinarily explode in the upper atmosphere, and most or all of the solids are vaporized. Objects with diameters over 50 m (164 ft) strike the Earth approximately once every thousand years, producing explosions comparable to the one known to have detonated above Tunguska in 1908. At least one known asteroid with a diameter of over 1 km (0.62 miles), (29075) 1950 DA, has a possibility of colliding with Earth on March 16th 2880, with a Torino Scale rating of two.


The Torino Scale is a method for categorizing the impact hazard associated with near-Earth objects (NEOs) such as asteroids and comets. It is intended as a tool for astronomers and the public to assess the seriousness of collision predictions, by combining probability statistics and known kinetic damage potentials into a single threat value. The Palermo Technical Impact Hazard Scale is a similar, but more complex scale.

The Torino Scale uses a scale from 0 to 10. A 0 indicates an object has a negligibly small chance of collision with the Earth, compared with the usual "background noise" of collision events, or is too small to penetrate the Earth's atmosphere intact.

 A 10 indicates that a collision is certain, and the impacting object is large enough to precipitate a global disaster. Only integer values are used.

An object is assigned a 0 to 10 value based on its collision probability and its kinetic energy (expressed in megatons of TNT).

The Torino Scale was created by Professor Richard P. Binzel in the Department of Earth, Atmospheric, and Planetary Sciences, at the Massachusetts Institute of Technology (MIT).

The first version, called "A Near-Earth Object Hazard Index", was presented at a United Nations conference in 1995 and was published by Binzel in the subsequent conference proceedings (Annals of the New York Academy of Sciences, volume 822, 1997.)

A revised version of the "Hazard Index" was presented at a June 1999 international conference on NEOs held in Torino (Turin), Italy. The conference participants voted to adopt the revised version, where the bestowed name "Torino Scale" recognizes the spirit of international cooperation displayed at that conference toward research efforts to understand the hazards posed by NEOs. ("Torino Scale" is the proper usage, not "Turin Scale.")

Due to exaggerated press coverage of Level 1 asteroids such as 2003 QQ47, a rewording of the Torino Scale was published in 2005, adding more details and renaming the categories: in particular, Level 1 was changed from "Events meriting careful monitoring" to "Normal".

 

 
Current Torino Scale

The Torino Scale also uses a color code scale: white, green, yellow, orange, red.
Each color code has an overall meaning:


NO HAZARD (white)
0. The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage.
NORMAL (green)
1. A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0.
MERITING ATTENTION BY ASTRONOMERS (yellow)
2. A discovery, which may become routine with expanded searches, of an object making a somewhat close but not highly unusual pass near the Earth. While meriting attention by astronomers, there is no cause for public attention or public concern as an actual collision is very unlikely. New telescopic observations very likely will lead to re-assignment to Level 0.
3. A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
4. A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of regional devastation. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away.
THREATENING (orange)
5. A close encounter posing a serious, but still uncertain threat of regional devastation. Critical attention by astronomers is needed to determine conclusively whether a collision will occur. If the encounter is less than a decade away, governmental contingency planning may be warranted.
6. A close encounter by a large object posing a serious but still uncertain threat of a global catastrophe. Critical attention by astronomers is needed to determine conclusively whether a collision will occur. If the encounter is less than three decades away, governmental contingency planning may be warranted.
7. A very close encounter by a large object, which if occurring this century, poses an unprecedented but still uncertain threat of a global catastrophe. For such a threat in this century, international contingency planning is warranted, especially to determine urgently and conclusively whether a collision will occur.
CERTAIN COLLISIONS (red)
8. A collision is certain, capable of causing localized destruction for an impact over land or possibly a tsunami if close offshore. Such events occur on average between once per 50 years and once per several thousand years.
9. A collision is certain, capable of causing unprecedented regional devastation for a land impact or the threat of a major tsunami for an ocean impact. Such events occur on average between once per 10,000 years and once per 100,000 years.
10. A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean. Such events occur on average once per 100,000 years, or less often.