Torino Scale
Encyclopedia
The Torino Scale is a method for categorizing the impact hazard associated with near-Earth object
s (NEOs) such as asteroid
s and comet
s.
It is intended as a communication 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 an integer 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 the kinetic energy
(expressed in megatons of TNT
) of the possible collision.
The Torino Scale is defined only for potential impacts less than 100 years in the future.
"For an object with multiple potential collisions on a set of dates, a Torino Scale value should be determined for each date. It may be convenient to summarize such an object by the greatest Torino Scale value within the set."
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, 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".
No object has ever been rated above level 4; the currently highest-scaled objects are only level 1 (see below).
are estimated to be in the 3–10 megaton
range. The biggest hydrogen bomb ever exploded, the Tsar Bomba
, was around 50 megatons.
The 1883 eruption of Krakatoa
was the equivalent of roughly 200 megatons.
The Chicxulub impact
, believed by many to be a significant factor in the extinction of the dinosaurs, has been estimated at 100,000,000 megatons.
. It has about a 1 in 1750 chance to hit the Earth during June 2048. This translates into a 0.057% chance to hit (or 99.943% to miss). The asteroid is estimated to have a diameter of 130 meters, and travels through space with a speed of 15.63 km/s relative to the Earth.
has been rated since February 2011 at Torino scale 1. As of September 2011, it has a 1-in-625 chance of impact in 2040.
Near-Earth object
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to...
s (NEOs) such as asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s and comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s.
It is intended as a communication tool for astronomers
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
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
Palermo Technical Impact Hazard Scale
The Palermo Technical Impact Hazard Scale is a logarithmic scale used by astronomers to rate the potential hazard of impact of a near-earth object . It combines two types of data—probability of impact, and estimated kinetic yield—into a single "hazard" value...
is a similar, but more complex scale.
Overview
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, compared with the usual "background noise" of collision events, or is too small to penetrate the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
intact. A 10 indicates that a collision is certain, and the impacting object is large enough to precipitate a global disaster. Only integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...
values are used.
An object is assigned a 0 to 10 value based on its collision probability and the kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
(expressed in megatons of TNT
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
) of the possible collision.
The Torino Scale is defined only for potential impacts less than 100 years in the future.
"For an object with multiple potential collisions on a set of dates, a Torino Scale value should be determined for each date. It may be convenient to summarize such an object by the greatest Torino Scale value within the set."
History
"The Torino Scale was created by Professor Richard P. BinzelRichard P. Binzel
Richard "Rick" P. Binzel is a Professor of Planetary Sciences at the Massachusetts Institute of Technology. He is the inventor of the Torino Scale, a method for categorizing the impact hazard associated with near-Earth objects such as asteroids and comets.Binzel was awarded the H. C. Urey Prize...
in the Department of Earth, Atmospheric, and Planetary Sciences, at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
(MIT). The first version, called "A Near-Earth Object Hazard Index", was presented at a United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
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
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...
), 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, 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. |
No object has ever been rated above level 4; the currently highest-scaled objects are only level 1 (see below).
Impact energy comparisions
The impacts which created the Barringer Crater or the Tunguska eventTunguska event
The Tunguska event, or Tunguska blast or Tunguska explosion, was an enormously powerful explosion that occurred near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia, at about 7:14 a.m...
are estimated to be in the 3–10 megaton
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
range. The biggest hydrogen bomb ever exploded, the Tsar Bomba
Tsar Bomba
Tsar Bomba is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. It was also referred to as Kuz'kina Mat , in this usage meaning "something that has not been seen before"....
, was around 50 megatons.
The 1883 eruption of Krakatoa
Krakatoa
Krakatoa is a volcanic island made of a'a lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. The name is used for the island group, the main island , and the volcano as a whole. The island exploded in 1883, killing approximately 40,000 people, although some estimates...
was the equivalent of roughly 200 megatons.
The Chicxulub impact
Chicxulub Crater
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...
, believed by many to be a significant factor in the extinction of the dinosaurs, has been estimated at 100,000,000 megatons.
Currently non-zero
is an asteroid which is listed on the Near Earth Object Risk List with a Torino Scale of Level 1. The object was discovered on 12 November 2007, by the Catalina Sky SurveyCatalina Sky Survey
Catalina Sky Survey is a project to discover comets and asteroids, and to search for Near-Earth objects. More specifically, to search for potentially hazardous asteroids , that may pose a threat of impact.-Mission:...
. It has about a 1 in 1750 chance to hit the Earth during June 2048. This translates into a 0.057% chance to hit (or 99.943% to miss). The asteroid is estimated to have a diameter of 130 meters, and travels through space with a speed of 15.63 km/s relative to the Earth.
has been rated since February 2011 at Torino scale 1. As of September 2011, it has a 1-in-625 chance of impact in 2040.
Downgraded to zero
- 2003
- was rated level 1 on 30 August 2003 and removed from the Sentry Risk Table on 14 September 2003.
- 2004
- (99942) Apophis (a ≈350 mMetreThe metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...
near-Earth asteroid) became the first object rated level 2 on 23 December 2004, and was subsequently upgraded to level 4 — the current record for highest Torino rating. It will pass quite closely to the Earth on 13 April 2029 without an impact. It retained a rating of level 1 for a 2036 encounter due to the orbital uncertainties introduced by the gravitational deflection until August 2006, when Apophis was downgraded to 0.
- (99942) Apophis (a ≈350 m
- 2006
- (using an observation arc of 475 days) was upgraded to level 2 in February 2006 for a possible 2102 encounter, making it the second asteroid rated above level 1. It was downgraded to 0 after further observations.
- 2008
- was rated level 1 until 14 February 2008.
- 2009
- 2009 KK2009 KK2009 KK is an asteroid which was listed for several weeks in May and June of 2009 on the NASA Near Earth Object Program Current Impact Risk List with a rating on the Torino Scale of Level 1. On 22 May 2009, it was listed as the second near-earth object assessed above Level 0 for potential impacts...
was rated level 1 after its discovery in May 2009, and downgraded to 0 on 17 June 2009. - was rated level 1 after its discovery on 17 November 2009, and downgraded by the end of November.
- 2009 YG was rated level 1 after its discovery on 17 December 2009, and downgraded to 0 by the end of December.
- 2009 KK
- 2010
- was rated level 1 in February 2010, and downgraded to 0 on 9 April 2010. The chances of an actual collision with an asteroid like YU55 (~400 meters in diameter) is about 1 percent in the next thousand years.
- was rated level 1 in in December 2010, and downgraded to 0 on 2 January 2011.
- 2011
- was rated level 1 in February 2011.
- was rated level 1 on 28 September 2011, but downgraded to 0 a few days later.
- is an asteroid with a diameter of 2.6 km, which was rated level 1 on October 27, 2011, but downgraded to 0 a few days later.
External links
- The Torino Impact Hazard Scale
- NASA Ames: Asteroid and Comet Impact Hazards: The Torino Scale
- NEODyS Impact Risk Page – NEODyS current risk list
- NEODyS Impactor Table
- NASA Near Earth Object Program: Impact Risk – NASA Near Earth Object Program current risk list
- Torino Scale
- New Scientist: "Row erupts over asteroid press scare" (18 September 2003)
- The Torino Scale
