NASA's fireball records show that the meteor exploded with 2.8 kilotons of force on June 21 at 01:16 UTC over a number of Russian cities including Lipetsk, which is south-east of Moscow. The explosion size correlates to a smallish asteroid of about 4 metres (13 feet) in diameter, which is a bit of a baby compared to the 20 metre (65 feet) asteroid that exploded back in February 2013 over Chelyabinsk, Russia. ... Although we don't know yet if any of the fragments reached Earth's surface, we do know that the intense explosion caused by the friction in the air...