Within a century – the blink of an eye in geological terms – the ejected material had come together to form a new world: our moon.Ĭomparison of lunar and terrestrial rocks supports the giant impact theory – although it remains poorly understood, and not everyone accepts it happened at all.Ĭlick to watch simulations of the collision by Robin Canup of the Southwest Research Institute in Boulder, Colorado and colleagues. Much of the mantle and crust of both planets was blown off into space, while Theia's iron core sank into Earth's. But its sheer size made for a truly colossal blow. This body, dubbed Theia, seems to have hit the Earth quite slowly compared with asteroid impacts like Chicxulub, and probably at an oblique angle. Just as things were settling down, along came a second planet, about one-tenth as massive as the Earth. At that time, the solar system was newly formed and the Earth's surface still cooling from its initial molten state. The most catastrophic blow ever dealt to the Earth probably came when it was very young, some 4.5 billion years ago. (Image: Everett Collection / Rex Features) Krakatoa, rated 6 on the VEI, was equivalent to about 200 megatons of TNT – at least three times as much as Tsar Bomba. Each step on the scale represents a tenfold increase in explosive effect. Volcanic eruptions are measured on the Volcanic Explosivity Index, which goes from 0 (weakest) to 8 (strongest). Krakatoa itself was virtually destroyed, although later eruptions have created a new island in the same place.Īt this point we have to switch scales. Tens of thousands were killed and many more injured sailors in the Sunda strait, for example, were deafened by the eruption. On the most violent day, 27 August, there were four enormous explosions, audible up to 4000 kilometres away. One of the most famous – and largest – explosions in recent history was the 1883 eruption of Krakatoa, a volcanic island in the Sunda strait, a narrow strip of sea between the Indonesian islands of Java and Sumatra.įollowing months of escalating activity, the volcano erupted in late August. Carpet-bombing an area with small bombs does much more damage. Nukes this large are very heavy, release too much fallout and in any case radiate much of their destructive energy into space. It seems unlikely that we will ever build a bigger nuclear weapon. In the event, it may have yielded 57 megatons – which would have made it just under four times as destructive as the Tunguska meteorite. The bang could have been even bigger: Tsar Bomba was originally intended to produce a 100-megaton explosion, but was redesigned to reduce the amount of radioactive fallout created. Windows were broken 900 kilometres away, and the mushroom cloud rose 64 kilometres above the ground.Īfterwards, a visitor to the blast site said, "The ground surface of the island has been levelled, swept and licked so that it looks like a skating rink." The Soviet-built weapon blew up over the Novaya Zemlya archipelago off the north coast of Russia with a flash of light that was visible 1000 kilometres away. The biggest human-made bang of all time was the explosion in October 1961 of the Tsar Bomba hydrogen bomb.
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