Emergency services refuse to comment cause of extraordinary blast in the dark sky.
As usual there is outlandish speculation about an alien visit, but there is genuine puzzlement and disagreement among experts over the mystery object.
The sensational discovery could lead to a much clearer understanding of a blast which was 1,000 times more powerful than the Hiroshima bomb.
Startling new details emerge of the most mysterious of Siberia's newly created giant permafrost holes.
Here we go back in time and remember 13 remarkable moments of 2013.