Bus-sized asteroid to pass by Earth
27 January 2012 Last updated at 09:02 GMT
Astronomers are watching for an asteroid the size of a double-decker bus which will pass within 70,000km (43,500 miles) of Earth on Friday.
Gareth Williams, of the Minor Planet Centre, told Radio 5 live Morning Reports: "There's absolutely no chance of it hitting us."
He explained: "It's way above the outer reaches of the atmosphere. Even if it were on a trajectory that took it into the atmosphere... objects of that size generally break apart in the upper atmosphere."
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Morning Reports broadcasts daily 0500 to 0530 on Radio 5 live.