Go stock up on Appophis or not?

Answer

Dear Wendy,

Currently, according to NASA (www.nasa.gov), there is one in 45,000 chance that asteroid 99942 Apophis will collide with Earth on April 13, 2036. About a year later, the thing comes close again, but the chance of impact is much smaller. These estimates are based on more than 700 observations of the asteroid over about two years. The longer an object is observed, the more accurately one can determine its trajectory, and therefore the better one can say how big the chance of a collision is. The current values ​​put Apophis on the lowest rung of the collision risk scale. This means that the probability of colliding with Apophis is no greater than the probability of colliding with an undiscovered object before. Apophis (then known by the provisional name 2004 MN4) made the news at the end of December 2004 when, based on the few observations available at the time, a collision probability of one in 37 was obtained. This placed the asteroid higher on the risk scale than any object ever. However, in the days and weeks that followed, more sightings allowed for more accurate predictions of the orbit, and the likelihood of impact decreased. It is not unlikely that it will fall further in the coming years, perhaps even to zero. But what if there was a collision? Apophis is an asteroid with a diameter of about 250 meters and a mass of about 21 million tons. If a collision were to occur, it would happen at a speed of approximately 45,000 km/h, which would produce an energy of 400 megatons. This is more than 25,000 Hiroshima atomic bombs. So the consequences on a regional scale would be enormous, but there is no danger to humanity as a whole.