Earth to have close brush with comet, page 11

The threat from this object seems to have passed. The fragments that have already passed us were the potentially dangerous ones. Anything that hasn't passed us yet is most likely too small to be a threat or even to spot with the best telescopes. The Spitzer did about the best job at picking up the actual cloud of comet dust that is following all of the fragments.

At this point, it would seem hopeful to even get a decent metoer shower our of the dust around May 22-25 from this comet.

However, there have been some questions about the next known threats that are of concern. There is a large Asteroid (2004 XP14) that is expected to pass the earth at a distance of about 280,000 miles on July 3rd. This object has not been seen since last year, so expectations are based on its' last sighting more than a year ago. That would be of minor concern.

The biggest current threat that we know of faces us Friday April 13th, 2029 from Asteroid Apophis when it is expected to pass us at a mere 20,000 miles. That is incredibly difficult to calculate such a close pass 23 years from now. 20,000 miles is closer than most satellites that are in orbit of the earth. This is the biggest known threat in any of our lifetimes.

The chances are that if we are ever to be hit by an asteroid, that NASA will only know about it weeks before impact. That is not enough time to divert it or destroy it. The only thing that could be done at that point would be to evacuate the impact site and surrounding areas. Keep in mind that the chances of an object hitting us that could wipe out a continent are extremely small. The chances are much, much bigger that an object the size of large house could cause an impact and explosion about the size of Hiroshima. In such an event, the damage would be limited and the crater would be about the size of the famous crater in Arizona.

However, if by some chance Apophis were to impact the earth, the devastation would be quite broad. An impact in the ocean would be the worst destroying most coastal lands up to an elevation of 100 ft around the ocean that it would impact and much higher on the coastal regions near to the impact. On land, it would probably destroy a western state in the U.S. or a small country somewhere else in the world.

The movies always portray the "Big One". The reality is that a much smaller impact is thousands of times more probable.

As for an asteroid impactor in the near future that actually threatens life....there are none known.