RT News update: Fireball was 40 tons before it entered atmosphere, not 10, and the blast was more powerful than a nuke.
16:19 GMT: The fireball that hit Russia’s Urals is the largest rock to strike the planet since 1908, Nature Magazine says. The blast was even more powerful than North Korea’s recent nuclear test, added the UK journal. Unlike the Russian Academy of Science, it estimated that the mass of the fireball was around 40 tons before it entered the atmosphere. Russian scientists put the mass at 10 tons.