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Re: Asteroid Will Miss Earth By Comfortable Distance In 2028



the similarity that i note is that dr. marsden hasn't learned from his
earlier neo prognostic excursions...then again, perhaps he was indeed aware
of the circus that would unfold--excluding, of course, his having been
corrected within a day of his pronouncement. hmmm...in any event, it would
seem that the media has not been alone in blowing things out of proportion.
   

just to clarify, i am not an advocate of attempting to deceive the public;
i am, however, in favor of an approach that includes spending a day or two
in consultation with one's colleagues before disseminating to the general
media "(near) earth shattering" press releases--especially when pertaining
to events decades hence.  

-darryl



At 10:45 PM 3/16/98 +0000, you wrote:
>I think Brian Marsden did the right thing, but the news media seems to blow
>things out of proportion.
>
>This situation with Asteroid 1997 XF11 is very similar to Comet Swift-Tuttle
>from about 5 years ago.  Comet Swift-Tuttle was recovered in late 1992, and
>prelimary analysis by Brian Marsden indicated a chance (albeit a very
>small chance) that the comet could collide with the Earth in the year 2126.
>The news media got wind of this and trumpeted an Earth impact in their
>headlines, often leaving out the details that there was a 
>large error margin and that that there was a very low probablity of impact.  
>Additional observations of the comet were 
>obtained, including matching the comet up with a previous appearance in
1737.  
>Based on the additional data, Marsden recomputed the comet's orbit and
>found the comet would miss the Earth by a comfortable 15 million
>miles in 2126, and retracted the collision possiblity.
>
>Note the similarity with 1997 XF11?
>
>More details on the story is available here:
>
>http://www.as.wvu.edu/~jel/skywatch/swfttle.html
>
>Then there was Comet Shoemaker-Levy 9.  The comet was discovered near
>Jupiter in 1993.  There was a large error margin with the initial orbit,
which
>was refined over time as more observations were made.  Marsden first
>determined that the comet was in a temporary orbit around Jupiter.  Later
on, 
>he determined that half of the fragments could possibly collide with Jupiter.
>Don Yeomans and Paul Chodas then chipped in, and they concluded that the
>entire comet train would impact Jupiter with a 64 percent probablity.
>With additional observations, the impact probablity became 100%, and the
>rest was history.
>
>The fact is, when a new object is discovered, there will be a large leeway
>in its orbit determination, which will get refined over time.  There will be
>more instances of Comet Swift-Tuttle and asteroid 1997 XF11 in the future - 
>it is only inevitable.  The thing to make clear is up front is the initial 
>orbit is "work in progress" and there are inherent large errors initially 
>which will decrease with time as new data is obtained.
>
>Ron Baalke 
>
References: