The meteor that caused devastation in the Russian town of Chelyabinsk could have struck the British Isles if it had entered the Earth's atmosphere at a slightly different time of day, according to astronomers.
They said the impact on a larger city such as Dublin or Belfast would have been devastating.
If the much-larger asteroid 2012 DA14, which grazed Earth later that day, had hit the planet, the impact would have been much worse, completely obliterating any city it struck.
The revelation, based on an analysis of the Earth's rotation, comes as scientists revealed they are planning a state-of-the-art detection system to give warning of incoming asteroids and meteorites.
The announcement of the decision to build the Asteroid Terrestrial-Impact Alert System, or Atlas, on Hawaii was made after the meteorite crash in Russia on Friday, and the close encounter with the 50m-diameter asteroid 2012 DA14 that swept to within 27,350km of Earth.
The fact that the two events happened together has been dismissed as "a cosmic coincidence" by scientists.
Nevertheless, astronomers - many gathered at the American Association for the Advancement for Science annual meeting in Boston - have been quick to reassure the public that they have plans to provide warnings of future impacts.
The Atlas detector, which is to be constructed with the help of a US$5 million ($5.9 million) grant from Nasa, will consist of eight telescopes fitted with powerful cameras, to be built on Hawaiian islands where the clear air makes accurate observations particularly easy.
John Tonry, a professor of astronomy at Hawaii University, said that Atlas, which is scheduled to begin operations in 2015, would have an extremely high sensitivity, which he compared to the detection of a match flame in New York City when viewed from San Francisco.
He predicted the system would give a one-week warning for a small asteroid, which he called "a city killer", and three weeks for a larger "county killer".
Tonry added: "That is enough time to evacuate the area of people, take measures to protect buildings and other infrastructure, and be alert to a tsunami danger generated by ocean impacts."
The previous time that Earth was known to have been struck by a meteorite was in 1908 when a huge blast - the equivalent of a large atomic bomb - in the Tunguska region of Siberia flattened more than 80 million trees. It is thought a comet more than 100m in diameter was responsible.
The announcement of the construction of Atlas came as Russia said it was sending more than 9000 workers to the region around Chelyabinsk in the Ural Mountains. President Vladimir Putin ordered the operation after it was revealed that about 1200 people, including 200 children, were injured in the blast. Most are thought to have suffered cuts and lacerations from shattered glass. More than 50 people were still in hospital.
Russian officials have estimated that the blast, which was preceded by a huge fireball that streaked across the evening sky, has caused damage of around US$30 million.
More than 4000 windows were blown out including many at schools where pupils were in their classrooms. Video footage has shown screaming children streaming from schools. A large fragment of the meteorite is believed to have crashed into a frozen lake near the town of Chebarkul.
-ObserverBy Robin McKie