Satgen 526 Lost Meteors Return ?  by GM4IHJ  (BID SGEN526) 1999-04-24

Satgen 525 discussed the way that Comets and their debris trails can
be redirected, when their orbits are shifted by changes in their
harmonic relationship to that of the planet which captured them when
they first entered the inner solar system , from the Kuiper Belt or
the Oort Cloud, comet nurseries.

>From time to time. Meteor shower which are the product of the Earths
encounters with Comet debris streams, change the timing and the
location of the point where they cross the Earth orbit around the Sun.
Most often these changes can be credited to a close encounter with a
planet as they came in towards the Sun or, as they exited out from the
Sun.

But if the orbit of the debris stream is subject to a big change . 
This can result in the generation of what appears to be a new
debris stream which intercepts the Earths orbit at a different date
and or , location from that used formerly. Or , more dramatic still,
the meteor stream may seem to vanish because it no longer comes close
to the Earths path, going over or below it at some considerable
remove.

Just what has happened in the case of the June Draconids/Bootes shower
( 27th June to 30th June , peaking 28th June ,  above the horizon all
day and associated with Comet Pons-Winnecke), is uncertain. Being a
comet of the Jupiter family, its period is about 6.16 years, which
causes it to undergo strong disturbance from Jupiter. For while it
does not necessarily go all that close to Jupiter , its slow motion at
aphelion near Jupiters orbit , results in the Comet and Jupiter
remaining near together for a lengthy period. Such that aphelion near
Jupiter stays the same, but perihelion distance near the Sun increases
quite markedly. Causing eccentricity to decrease and orbital period to
increase.

All this disturbance has made the annual meteor shower due to this
Comet, highly variable. In the first quarter of the 20th century , it
produced some excellent meteor showers . Then for 70 years it
virtually disappeared . Only to reappear in 1998,  with an excellent
display peaking at about 100 meteors/hour.

At first glance this does not look like a Comet which has changed its
orbit. But it certainly looks as if there has been severe disturbance
. Such that the debris stream was temporarily directed away from the
Earth, only to resume its old ways in order to meet the earth again in
1998. There is of course a very slight possibility that this is a new
stream entirely. But whether new or old. Will it reappear in 1999 ?
The Comet is due back near the Earth in 2000. So perhaps this is a
good omen. Just maybe, radio meteor scatter listeners and visual
meteor observers will both be treated to a lively shower around June
28th this year. But with a Comet as disturbed as Pons-Winnecke, there
is no guessing what will happen.