That will leave a mark

From Siberia let's take a little trip.  It is not a short distance, so I suggest we go real fast; I don't have a lot of time to waste, and I am sure you are in a hurry also.  We are going to the desert southwest of the United States, in the state of Arizona, to a fairly substantial hole in the ground named Barringer Crater, also known as Meteor Crater.

 

About 50,000 years ago, an object penetrated the atmosphere over the Colorado Plateau.  This asteroid had an estimated diameter of about 50 meters, about the same size as the Tunguska object.  However, whereas the Tunguska asteroid was made of rock and exploded several miles above the surface, the Barringer asteroid was composed of nickel-iron and therefore could handle much more atmospheric stress.  The Barringer object survived to impact the surface.  Early research indicated an impact speed of over 72,000 kilometers per hour, but later models suggest a speed a little more than half that.  To put that speed in perspective, the SR-71 had a top speed of about 3,600 kilometers per hour.  When the Barringer object impacted, its mass of perhaps 150,000 metric tons of nickel iron vaporized.  That explosion tore open a wound in the earth more than a kilometer in diameter, and well over 150 meters deep. The rim of the crater is almost 50 meters above plateau around it.  All life was extinguished from the impact site to beyond three kilometers, and everything combustible within nearly ten kilometers was incinerated.  The shock wave that traveled through the air from ground-zero flattened everything for more than 130 square kilometers.

 

Neither the Tunguska explosion nor the Barringer impact was sufficient to cause any global damage.  Neither was big enough to cause any real problems outside their own region.  However, put either event into a modern population center and see how many people are obliterated.  A rock from space landing on your head could ruin your whole day.

 

Neither event is by any means a worst case scenario; things could be much worse, because both these rocks were small.

 

Next time let’s look for the big boys.