Torino Scale

Most people, especially those of us living in California, have heard of the Richter Scale, which measures the intensity of Earthquakes.

Much less well known is the Torino Scale.

What is the Torino Scale? It is a scale designed to measure the danger posed by asteroids in their wandering orbits about the sun: the larger the number, the higher the likelihood that a given asteroid is going to smack into the planet.

No Hazard 0 (White Zone)

The likelihood of a collision is zero, or is so low as to be effectively zero. It 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 1 (Green Zone)

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 nonexistent.

Meriting Attention by Astronomers 2 (Yellow Zone)

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 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 officials is merited if the encounter is less than a decade away.

Threatening 5 (Orange Zone)

A close encounter posing a serious, but still uncertain threat of regional devastation. Critical attention by astronomers is needed to determine conclusively whether or not 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 or not 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 or not a collision will occur.

Certain Collisions 8 (Red Zone)

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 1000 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.

On the Thursday before Christmas 2004, asteroid 2004 MN4 was given a 2 on the Torino Scale, when preliminary measurements indicated it had a 1 in 300 chance of hitting the Earth. By the day after Christmas, the odds had dropped to 1 in 40 and it had risen on the scale to 4. Asteroid MN4 was about 1300 feet across (the asteroid that made the mile wide crater in Arizona that is now a tourist attraction was only about 150 feet across). Upon impact, it would have released 2200 megatons of energy. The largest nuclear device ever exploded on Earth so far was only 50 megatons. Based on preliminary calculations it looked as if asteroid 2004 MN4 was going to hit on April, Friday the thirteenth, 2029—only sixteen years from now.

By the next Monday, however, with more orbital data having come in, the scientists at NASA and a laboratory in Italy were able to determine that the asteroid’s orbit was not a danger to Earth at all and so there was nothing to worry about, at least from this asteroid. It dropped to 0 on the Torino Scale.

What one can worry about are all the asteroids that haven’t been discovered yet—like the one that smashed into Russia recently while everyone was looking at another asteroid that was swinging perilously close.

But the funding for looking out for passing space rocks is not large and it will likely be decades before all the potentially dangerous asteroids have been tracked and cataloged. So for now, we can predict large meteor strikes about as well as we can predict earthquakes. Asteroids are God’s way of asking us, “So how’s that space program of yours coming along? Might want to speed it up a bit, don’t you think?”