Extraordinary 24 hours for astronomers
16 February 2013 Last updated at 12:51 GMT
An asteroid as large as an Olympic swimming pool has raced past the Earth at a distance of just 27,700km (17,200mi) - the closest ever predicted for an object of that size.
It passed far closer than the geosynchronous satellites that orbit the Earth, but there was no risk of impacts or collisions.
The asteroid's arrival was preceded by a damaging meteor event in Russia on Friday.
But the meteor's path suggested the two events were entirely unrelated - just a "cosmic coincidence", as Alan Fitzsimmons of Queens University Belfast told BBC News.
Beth McLeod reports.