Kilotonne of TNT
A kilotonne of TNT is a unit of energy equal to the explosion of 1,000 tonnes of TNT, used to describe impacts and airbursts.
A kilotonne of TNT is a way of expressing large amounts of energy by comparing them with an explosion of 1,000 tonnes of the chemical explosive TNT. One kilotonne is about 4.2 trillion joules. A megatonne is a thousand times more.
The unit is used for meteor airbursts and impacts because it gives a feel for their power. The Chelyabinsk airburst of 2013 released roughly 440 to 500 kilotonnes, about 30 times the energy of the atomic bomb dropped on Hiroshima, but most of it was spread high in the atmosphere. The Tunguska event of 1908 is estimated at roughly 3 to 15 megatonnes. The impact that ended the age of the dinosaurs released something like 100 million megatonnes.
Most of this energy comes from the meteoroid's speed. A rock moving at 20 kilometres per second carries about 50 times more energy than the same mass of TNT.
Related terms
Level: Explorer Ages 10 and up