Asteroid strike threat 'worse than we thought'
Scientists say the threat of another asteroid strike like the one that hit Russia in February this year is much higher than was previously thought.
Asteroids, meteors and meteorites
- Asteroids are small bodies that orbit the Sun as the Earth does
- Larger asteroids are called planetoids or minor planets, smaller ones often called meteoroids
- Once any of these enters our planet's atmosphere, it becomes a meteor
- Many meteors break into pieces or burn up entirely as they speed through the atmosphere
- Once meteors or fragments actually impact the surface, they become meteorites
Researchers writing in the science magazine Nature say that space rocks of a similar size to the one that exploded over Russia are hurtling into the Earth's atmosphere surprisingly often.
An international team found that in the past 20 years, about 60 asteroids up to 20 meters wide had smashed into the Earth's atmosphere. This number was far more than was previously thought.
Most of them went undetected because they exploded over the ocean or in very remote areas.
This suggests that up until now, experts have underestimated the risk from asteroids of this scale.
The scientists say early warning systems should be put in place that can find when and where these rocks may hit.