On December 11, 2012, I wrote: “I am writing this column before the date on which the world is supposed to end, December 21, 2012 . . . The end of the world is scheduled on the Mayan calendar for 21122012. The Mayan calendar comes to the end of the ‘long count’ on the December 21, 2012, and it is believed that the world may end the following day.”

Now, unless you are a politician (and, thus, too thick to notice), you probably know that the world did not end on the December 21, 2012. In fact, it did not even wobble.

Anyway, if you happened to give away all your worldly goods, sacrifice your pet dogs and tell your boss to shove it on December 20, 2012, maybe it is all worthwhile since now the world is going to change, apparently, on the September 23, 2015.

The prophecies are interpreted from the Bible, they say. However, the people spreading these rumours do not talk about the world ending but rather about a cataclysmic event that will change the world. An example would be if an asteroid hit the earth, resulting in climate change. (To be quite candid, I do not know why people rabbit on about climate change. It is a simple fact that the climate of Johannesburg varies from months of dryness to months of torrential rain, from –8 °C to 40 °C all in the space of a year. Nobody thinks this is unusual.)

Back to cataclysmic events. Let us think about an asteroid hitting the earth. We will choose an asteroid called 87 Silvia, the eighth-largest asteroid in the asteroid belt, and assume that it is going to whack into the earth. 87 Silvia has a mass of 1.4-million tons, and from 200 km above the earth it will hit ground zero at five times the speed of sound. The energy it will release will be 2 800 TJ.

Is this enough to destroy the earth? Well, on a most basic level, the atomic bomb dropped on Hiroshima on August 6, 1945, exploded with an energy of about 15 kt of TNT (63 TJ) and the bomb dropped on Nagasaki on August 9, 1945, exploded with an energy of about 20 kt of TNT (84 TJ).

Thus, the effect of 87 Silvia colliding with the earth will be about the same as the detonation of 33 World War II atomic bombs. But in terms of modern bombs, that is nothing.

Tsar Bomba (Russian), developed by the Soviet Union, had the yield of 50 megaton of TNT (210 Petajoules or 210 000 Terajoules). It was detonated at the Novaya Zemlya archipelago, at Sukhoy Nos. Novaya Zemlya is about 2 500 km from Norway. The bomb was detonated in the atmosphere and the mushroom cloud extended 64 km into the sky. All this was in 1961 and the world did not end, and nobody thinks this bomb caused any climate change. We can say that the collision of 87 Silvia will result in widespread damage; in atmospheric flight, the asteroid will break into many pieces owing to thermal and acoustic shock and, consequently, the population of a country may suffer some decimation, as did Russia in World War II. But the end of the world as we know it? Not likely.

One thing that can cheer us all up is that, if an asteroid does strike the earth, we in Southern Africa are used to it. Of the world’s ten biggest meteorite impact sites, we have the Vredefort impact site and the Morokweng Crater, in Kalahari. Not only this – the biggest meteor on earth is found at Hoba, near Grootfontein, in Namibia. It is not that big: 2.7 m × 2.7 m × 1 m. Interestingly, it did not leave a crater after landing.

So, what will make the world end? A series of volcanic eruptions? Had those and it did not end. I think probably mankind will end it. Some dangerous clown will miscalculate the effect of a nuclear explosion, the explosion will cause other explosions and, finally, the fusion explosion of the atmospheric hydrogen fuelled by gaseous separation of water. Remember, if you survive, you read it here first.