Torino scale

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.

Near-Earth objects with a Torino scale of 1 are discovered several times a year, and may last a few weeks until they have a longer observation arc that eliminates any possibility of a collision.

"[2] 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).

A revised version of the "Hazard Index" was presented at a June 1999 international conference on NEOs held in Torino (Turin), Italy.

Each color code has an overall meaning:[5] No incoming object has ever been rated above level 4, though over all of Earth's history impacts have spanned the full range of damage described by the scale.

For NASA, a unit of the Jet Propulsion Laboratory (JPL), the Center for Near-Earth Object Studies (CNEOS) calculates impact risks and assigns ratings in its Sentry Risk Table,[6] while another unit of JPL, Solar System Dynamics (SSD) provides orbital and close approach data.

[12] The Chicxulub impact, believed by most scientists to have been a significant factor in the extinction of the non-avian dinosaurs, has been estimated at 100 million (108) megatons.

Between 2000 and 2013, 26 atmospheric asteroid impacts with an energy of 1–600 kilotons were detected by the network of infrasound sensors operated by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization.

On December 24, 2004, 370 m (1,210 ft) asteroid 99942 Apophis was assigned a 4 on the Torino scale, the highest rating given to date, for an impact in April 2029.

[23] After additional observations allowed increasingly precise predictions, the Torino rating was lowered first to 1 in May 2006, then to 0 in October 2006, and the asteroid was removed from the Sentry Risk Table entirely in February 2008.

[6] Astronomers responded by scheduling observations with more powerful telescopes as the object recedes and gets dimmer, to determine its orbit with more precision and thus improve the impact risk prediction.