The two asteroids were going in opposite directions, so were not related.
While everyone was expecting and watching Asteroid 2012DA14, which missed Earth by 26,000 km (17,000 miles), another asteroid blasted through the atmosphere in Russia, injuring more than 1,000 people (mostly by shards of glass caused by the sonic boom). One estimate makes it out to be a 10 tonner (seems a bit small), traveling at 30 kilometers a second. Another astronomer, Margaret Campbell-Brown, claims ultrasound stations show it was 15m wide and around 40 tonnes. Nature quotes the same researcher talking about 15m and 7,000 tonnes. You can see we have a good grip on what happened. [UPDATE: Now it's 10,000 tons and 55 feet wide and stone. The largest object to hit in a century. WUWT. What about the ones that fell over the ocean wonders Jo? How would we know?]
It left a “contrail” and a flash that could be seen for 700km (see these videos –why are people filming while they drive?). It only “missed” by 30 – 50 kilometers and nobody knew it was coming. How little we know. One part of it broke off and smashed into a frozen lake, leaving a 6m [...]