(meteorobs) ejection velocities and ejection times

[Mikhail Maslov]

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

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

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

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

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

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

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

Yes, I meant just these favorable conditions in 2018 (especially) and
in 2025. In 2005 and 2011 C-E distance is about 0.03-0.04 AU, then it
will decrease to 0.015 in 2018 and 0.011 in 2025. And maybe that will
be last years with possible strong Giacobinid outbursts, later
perihelion distance of the comet will be shifted to 1.07 AU in 2037
and 1.10 AU in 2045.

Best regards, Mikail Maslov