[Prev][Next][Index][Thread]

Re: (meteorobs) Leonids 2000

In a message dated 10/19/00 3:22:38 AM Eastern Daylight Time, 
rmn@aaocbn.aaodot gov.au writes:

<< "This year will truly put the Asher-McNaught meteor-trail theory to the
 test ..." S&T 2000 Nov. p 111
 From the comments above, it is clear that we make no strong prediction,
 so unless substantial activity occurs well away from a dust trail
 encounter, there will be no test of our theory this year.  Only Ferrin,
 amongst those who have made predictions, has done so without consideration
 of the existence of dust trails.
  >>
Rob (and everyone else on the meteorobs list) --
    
    That S&T comment about " . . . the Asher-McNaught meteor trail theory 
truly being put to the test" this year, was that a year 2000 prediction 
concerning significant Leonid activity based on the meteor trail method was 
targeting the time frame from roughly 18 to 24 hours after the Earth passing 
the descending node of 55P/Tempel-Tuttle.  Previous to the publication 
describing the meteor trail method in great detail in journals such as "The 
Astronomer" and "WGN" I had never seen a prediction calling for any 
significant Leonid activity so far after the "traditional" time of the nodal 
crossing.  As we are all aware, from a historical standpoint, the Leonids are 
usually a very sharply peaked display and usually produce just a single 
"burst" of activity (be it a storm, or a much lower rate).

    Last year, many of the "Leonid pundits" called for the possibility of 
major activity on the morning of November 18.  David Asher and Rob McNaught 
targeted 2:08 UT, but in fairness, there were many others who also were 
predicting maximum within 10 to 20 minutes of this same time.  In one case, 
Dr. Edward K.L. Upton, of the Griffith Observatory in Los Angeles wrote an 
article in the popular glossy "Griffith Observer" and made a prediction that 
the Earth would interact with material shed by Tempel-Tuttle from its 1899 
perihelion.  He wrote:  

"The moment of encounter should be close to 2 a.m., Greenwich time, November 
18.  This shower will therefore not be seen in America, but all of Europe and 
all of Africa except the easternmost tip will be favorably positioned.  A due 
regard for the height of the radiant and likely weather conditions points to 
North Africa as the best observing location."  

    As we all now know, the 1999 Leonids reached their peak near 2:02 UT.  
The interesting point about Dr. Upton's article is that it appeared back in 
May 1977.  Upton's entire article (including an introduction by Dr. Ed Krupp 
and myself) is reprinted in the current Griffith Observer (November, 
2000/Vol. 64, No. 11).  

    Concerning the Leonids in 2000, most of the predictors have targeted the 
morning of November 17 (again around the node) as the most likely time for 
highest activity.  Rob and David's prediction for potential maximum activity 
occurring on the morning of November 18 pretty much has stood alone (although 
Esko Lyytinen and Tom Van Flandern have now also cited the morning of the 
18th for maximum activity, though taking a somewhat different approach than 
Rob and David).  

    The point that S&T tries to make is that if any surge of Leonid activity 
is observed on the morning of the 18th, that it should certainly should go 
some ways to help validate the meteor trail theory.  In a personal e-mail to 
both David and Rob, I commented that the meteor observing community owes both 
of them a debt of gratitude for being the first to step forward and point out 
the possibility of some unusual activity occurring on the morning of the 
18th.  Only a few years ago, the vast majority of observers would have 
concentrated all of their efforts on the morning of the 17th . . . and most 
would likely have not bothered to look again on the following morning!  As I 
pointed out in a message here a few weeks ago, this upcoming scenario of 
possible distinct/significant Leonid activity on two consecutive nights is 
rather unique in the modern history of the Leonids . . . and perhaps will 
only serve as a precursor to Rob and David's projection of multiple storm 
peaks in 2001!

    Concerning Dr. Ferrin's prediction of a major Leonid storm this year on 
the morning of the 17th, I should point out that it very much mirrors a 
similar prediction that he made concerning a possible storm of Giacobinid 
meteors for 1986.  In a letter to Sky & Telescope, published early that year 
(February or March . . . I don't have it at hand), Dr. Ferrin suggested even 
greater Giacobinid activity a year after the 500/hr rates observed from Japan 
in 1985.  He does not specifically mention his "isolines" method in his 
letter, but his reasons and conclusions for expecting a major Giacobinid 
display in 1986 seems to closely parallel his projection for major Leonid 
activity a year after last year's storm-level event.  As for the 1986 
Giacobinids, little or no activity was noted.

Echoing Rob's sentiments, I say regarding the Y2K Leonids: 
you'll only know what will really happened if you get out and look!
-- joe rao  

    
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html
Follow-Ups: