Asteroid/Comet Strike

Situation
An asteroid or comet has been detected and determined by the European Space Agency (ESA); International Astronomical Union (IAU); or the National Aeronautic Space Administration (NASA) will strike the earth, and being of sufficient mass and kinetic energy potential to alter present life on the planet Earth.

Classification of the specific type of strike will affect the response of the people.

An astrobleme creates an actual penetration of the earths crust. This will decimate cities. Later, volcanic ash, dust and acid rain caused by meteor debris would poison the oceans, kill vegetation and any remaining animal life, humans included. We would find it difficult if not impossible to survive.
An asteroid sufficient to create an astrobleme would cause a third of the earth to burn, including building, trees and grass. The acid rain from the asteroid debris would turn the oceans blood red and a majority of marine life would perish. The dust and ash thrown into the sky would block the light from the sun, the moon and the stars; animal life would die as food sources disappear.
Earth has been struck several times by large asteroids and others, which exploded in the atmosphere with devastating effects. The Chicxulub crater on the north shore of the Yucatan Peninsula in Mexico ended the life of dinosaurs, along with about 70 percent of life on Earth. It produced a global cloud of dust and sulfur gases that blocked sunlight and introduced Earth to a decade of near-freezing temperatures.
The Barringer Crater near Winslow, Arizona was created by a nickel-iron meteorite about 150 feet across, weighting roughly 300,000 tons and traveling at a speed of 40,000 miles per hour. The impact caused an explosion equivalent to 20 million tons (20 megatons) of TNT and left a chasm 570 feet deep.
In 1908 the Tunguska event in Siberia occurred when an asteroid or comet estimated at 200 feet wide and weighing about 100,000 tons exploded five miles above the Earth, releasing approximately 20-40 megatons of energy. An area the size of Rhode Island was devastated in the explosion, killing wildlife within 20 miles of the impact and creating fires that burned for weeks.
On March 23, 1989 an asteroid named 1989 FC with a diameter about 0.3 miles and a kinetic energy of over 1000 megatons passed within 430,000 miles of the Earth. This asteroid was not discovered until it had passed its point of closest approach, and only after calculating backwards its orbital path. Since then celestial bodies of similar sizes have been measured as coming within 62,000 miles of Earth.

The Torino Scale is used to assess asteroid and comet impact hazard predictions.

Torino Scale 0

The likelihood of a collision is zero, or well below the chance that a random object of the same size will strike the Earth within the next few decades. This designation also applies to any small object that, in the event of a collision, is unlikely to reach the Earth's surface intact.

Torino Scale 1

The chance of collision is extremely unlikely, about the same as a random object of the same size striking the Earth within the next few decades.

Torino Scale 2

A somewhat close, but not unusual encounter. Collision is very unlikely.

Torino Scale 3

A close encounter, with 1% or greater chance of a collision capable of causing localized destruction.

Torino Scale 4

A close encounter, with 1% or greater chance of a collision capable of causing regional devastation.

Torino Scale 5

A close encounter, with a significant threat of a collision capable of causing regional devastation.

Torino Scale 6

A close encounter, with a significant threat of a collision capable of causing a global catastrophe.

Torino Scale 7

A close encounter, with an extremely significant threat of a collision capable of causing a global catastrophe.

Torino Scale 8

A collision capable of causing localized destruction.

Torino Scale 9

A collision capable of causing regional devastation.

Torino Scale 10

A collision capable of causing global climatic catastrophe.

Consequences of impacts of various sizes.

Diameter (Meters)	Yield (megatons)	Consequences
<50m	<10	in upper atmosphere-most don't reach surface
75m	10-100	irons make crater like Meteor Crater; Stones produce airburst like Tunguska; land impacts destroy area size of city
160m	100-1000	Irons, stones hit ground; comets produce airbursts; land impacts destroy area size of large urban area (e.g. New York, Tokyo)
350m(1/5 mile)	1000-10,000	Land impacts destroy area size of small state; ocean impact produces mild tsunamis
700m	(1/2 mile) 10,000-100,000	Land impacts destroy area size of moderate state (e.g. Virginia); ocean impact makes big tsunamis
1700m (1 mile)	100000-1,000,000	Land impact raises dust with global implication; destroys area size of large state (e.g. California, France)

Meteorite Types

Iron: Primarily iron and nickel; similar to type M asteroids

Stony Iron: Mixtures of iron and stony material like type S asteroids

Condrite: By far the largest number of meteorites fall into this class; similar in composition to the mantles and crusts of the terrestrial planets

Carbonaceous Chondrite: Very similar in composition to the Sun less volatiles; similar to type C asteroids

Achondrite: Similar to terrestrial basalts; the meteorites believed to have originated on the Moon and Mars are achondrites

Effects

a. The earth's gravitational attraction cause meteors to enter the Earth's atmosphere at a minimum velocity of 5 miles a second, about forty times the speed of sound, and at such high velocities, friction in the atmosphere causes the surface of the body to melt and the air around it to become electrically charged, that gives rise to a phenomenon we call the fireball. In the last few seconds of luminous flight through the atmosphere, the fireball goes out, and the remaining material melts on the surface and solidifies to form a thin skin on the surface of the meteorite, which is called a fusion crust. The interior though has remained virtually unaltered.

b. If entry into the atmosphere results in an extremely shallow angle, a wall of flame erupts at the point of impact and rolls downrange for miles, incinerating everything in its path. It may also contact and skip across the earth's surface.

c. The environmental shock from a level 10 event, because of the energy levels, the debris that would be traveling at ballistic velocities, will affect all hemispheres at essentially the same time.

d. The impact can blast tons of sulfur-rich rock and dust high into the atmosphere, encircling the globe and igniting the skies. This burning debris will rain back down upon the earth, and the skies will be darkened for months, if not years, to come.

e. The sulfur and volcanic debris would mix together and once combined would return to the Earth laced by rain as acid which would poison the majority of fresh and salt water life and drastically reduce the availability of drinking water.

f. The shock waves will pull the tectonic plates apart creating substantial earthquakes and unleashing lava flows.

g. The shock waves will disrupt the dynamic equilibrium within many volcanos and cause their eruption, spewing volcanic ash falls; this creates lightning and all will contribute to the raging wildfires. All these events will enact together to increase the temperature, the environmental devastation will last for a long time and ninety percent of the world’s biomass burned, and two thirds of the world's species will disappear.

h. Should the meteor/comet break up in the atmosphere, several smaller meteorites will impact the Earth out of the projected impact zone of the larger meteorite. Each of these fractures will likely create their own independent series of catastrophes around the world.

i. Impacts that hit the water will create tsunamis that will travel around the world, thus intensifying ripple effect damage globally. These will cause the oceans to recede from the coasts temporarily, and as the tsunamis hit the continental shelf the waves will rise up as water is forced up over the land. These tsunamis can reach speeds of 700 miles per hour and ultimate elevations of 1500 feet high. Coastal areas will be effectively removed from the face of the planet, and waters can reach hundreds of miles inland, only to recede out to sea again. Similar in principle to the storm surge that occurs during a hurricane.

j. Windblast created by the hypersonic speeds of the approaching meteorites will level buildings and forests, and actually create vortices to pull in debris until it terminates with impact. Animal life, including humans that are in the proximity may suffer from the shockwave blast resulting in physical damage including deafness, blindness, respiratory failure, concussion effects, crushing effects from the air and sound disturbances or even death.

Probabilities of discovery

Scientists only know of a small fraction of the ones that exist. Ninety percent of the meteors and comets have not been found yet, let alone have had their orbits reliably calculated.

Back to the Knowledge Base