Earth has been hit 566 times over 20 years

This map uses data gathered from 1994-2013 and shows where small asteroids hit Earth's atmosphere and produced very bright meteors, technically called 'bolides' and commonly referred to as 'fireballs'. The objects ranged in size from about 1 metre (3 feet) to almost 20 metres (60 feet).

This map uses data gathered from 1994-2013 and shows where small asteroids hit Earth’s atmosphere and produced very bright meteors, technically called ‘bolides’ and commonly referred to as ‘fireballs’. The objects ranged in size from about 1 metre (3 feet) to almost 20 metres (60 feet).

A map released by NASA’s Near Earth Object (NEO) Program reveals that small asteroids frequently enter and disintegrate in Earth’s atmosphere with random spread around the globe.

Released to the scientific community, the map visualises data gathered by U.S. government sensors from 1994 to 2013. (‘Sensors’ probably means, or at least includes, spy satellites. Ed.)

The data indicate that Earth’s atmosphere was hit by small asteroids, resulting in a bolide (or fireball), on 556 separate occasions in a 20-year period.

Almost all asteroids of this size disintegrate in the atmosphere and are usually harmless. The notable exception was the Chelyabinsk event, which was the largest asteroid to hit Earth in this period.

Trail left by the Chelyabinsk meteor.

Trail left by the Chelyabinsk meteor.

The new data could help scientists better refine estimates of the distribution of the sizes of NEOs including larger ones that could pose a danger to Earth.

Finding and characterising hazardous asteroids to protect our home planet is a high priority for NASA, and is one of the reasons the agency has increased by a factor of 10 investments in asteroid detection, characterisation and mitigation activities over the last five years.

In addition, NASA has aggressively developed strategies and plans with its partners in the U.S. and abroad to detect, track and characterise NEOs.

These activities also will help identify NEOs that might pose a risk of Earth impact, and further help inform developing options for planetary defence.

The public can help participate in the hunt for potentially hazardous Near Earth Objects through the Asteroid Grand Challenge, which aims to create a plan to find all asteroid threats to human populations and know what to do about them.

NASA is also pursuing an Asteroid Redirect Mission (ARM) which will identify, redirect and send astronauts to explore an asteroid.

Among its many exploration goals, the mission could demonstrate basic planetary defence techniques for asteroid deflection.

Adapted from information issued by NASA’s Jet Propulsion Laboratory. Chelyabinsk meteor image courtesy Alex Alishevskikh under CC. Map courtesy Planetary Science.

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