The Asteroid Threat.


Asteroid Threat.

This planet of ours has often suffered incredible upheaval from occasional asteroid strikes. In many cases these strikes have come close to wiping out all living matter.


The certain fact is that sooner or later we are bound to be hit again. But would we survive?

     

Asteroids – the inevitable rendezvous.

Regarding the threat of asteroids there is but one reality – that eventually the Earth will be hit by one. When that day comes a single factor will decide whether we survive or not. It is the size of the asteroid. Small objects of only several metres diameter can devastate major cities. Medium objects of up to a kilometre can devastate continents. The very largest asteroids can exterminate all life on Earth!

Unimaginable disaster.

The devastation caused would also depend on the location of the impact. If for instance a 2 kilometre asteroid were to hit the sea it would raise a tidal wave of unimaginable proportions – up to 10 kilometres high. This would naturally pour across continents washing away towns and cities like sand castles on a beach. If on the other hand the impact were on land it could, according to some scientists, release enough energy to remove the entire Earth’s atmosphere.

Close encounters.

An illustration of how pressing the fears are is illustrated by the rising number of close misses within recent times. In September 2000 for instance there were no fewer than five near misses from asteroids that sailed by with no more than a weeks warning.

More close shaves.

In 1991, a small asteroid passed within just 100,000 miles of the Earth. Two years later in May 1993, another asteroid missed us by just 80,000 miles. The year 1994 saw two close shaves with asteroids that hurtled by at a distance of only 100,000 miles!  Although these distances may seem vast, in astronomical terms they represent no more than a bullet burn, the cosmic wink that sometimes separates us from outright disaster.

Tunguska.

In the early years of the 1900’s a fragment of a small meteorite devastated hundreds of square metres of a remote Siberian forest. A similar strike over a heavily populated city would produce millions of casualties in a catastrophe almost too fearful to contemplate.

Overdue impact.

The fact is that ever since the human race existed the danger from comets and asteroids has been an ever present reality. It is estimated that a major asteroid impact occurs every 25,000 years. Scientists believe the next strike is long overdue, and the unhappy truth is that we could be hit with absolutely no warning at all!

Early warning system.

Some attempt is now being made to set up an early warning system to detect planet threatening asteroids. However this is still a long way from knowing what to do if one were found to be on a collision course to hit us. If we had 10 years warning it is likely we might be able to deflect it with specially designed missiles. Unfortunately this capability would be severely shortened if the asteroid were detected within 2 – 5 years of impact. Even worse is the realisation that if we discovered an asteroid scheduled to hit us within 2 years there is certainly nothing we could do about it.

See our feature on the threat posed to our planet by Gamma Ray Bursts.

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