(meteorobs) ejection velocities and ejection times

[Skywayinc at aol.com]

In a message dated 10/8/04 12:47:18 AM Eastern Daylight Time, ast0 at mail.ru 
writes:

<< Also it would be very interesting to look at predictions for
 Giacobinids 2018 and 2025. >>

    I do not know of the situation regarding dust trails in 2018, but the 
circumstances regarding the orbit of the parent comet 21P/Giacobini-Zinner and 
Earth seem (at first glance) very favorable for producing some sort of enhanced 
Giacobinid activity.  In WGN  26-5 (October 1998), page 215, I noted that:

    "By far the favorable scenario is that of 2018.  Earth will follow the 
comet to the nodal crosing point by only 22.7 days, and the separation between 
the orbits of Earth and comet will be 0.017 AU (2,543,000 km.).  This is 
roughly midway between the C-E value for the storm observed from Europe in 1933 and 
for the heavy shower briefly seen from Japan in 1985.  Earth is due to arrive 
at the nodal crossing point at 0h UT on October 9, which would correspond to 
20h EDT (dark sky conditions) on October 8 along the United States east coast.  
Add to this the fact that the Moon will be at new phase, and observing 
conditions seem ideal!  Unfortunately, an approach to within 0.37 AU of Jupiter by 
21P/Giacobini-Zinner in February 2029 will cause a significant widening of C-E 
to 0.076 AU (11,367,000 km.) by 2038."

    Again . . . the above was based not on future interactions of Earth with 
dust trails, but solely on the position of the Earth relative to the orbit of 
the Giacobinid parent comet. So it would be interesting if a calculation was 
performed to indicate if we are indeed in a position to see anything unusual 
from the Giacobinids in 2018.

    And even with the favorable geometry noted above, some were still not 
convinced.  In a footnote to my comments above, Donald K. Yeomans of NASA's Jet 
Propulsion Laboratory was quoted as saying: 

"Still . . . I would not bet the farm that a meteor storm will occur."
-- joe rao