Satgen 189  Comet - Hit or Miss     by GM4IHJ                 6th Nov 92
The BID of this bull is sgen189  Please retain that BID if you retransmit

I have postponed Pt4 of Satellite Stabilization , in order to say
something about Comet Swift-Tuttle (S-T) whilst it is visible. The
connection between S-T and the August Perseids meteor shower, is well
established. So it was no great surprise , when following this years
excellent 11th Aug Perseids, S-T itself was sighted in late September 92
after an absence of 130 years. It is now visible in binoculars on clear
evenings in the constellation of Hercules , (viewing details below  V )
What is different about this return of S-T, is that it gives orbit
specialists much better prediction data, so they can now confidently
predict that S-T will return in 2116 AD and pass quite close to the Earth.
Needless to say, the Megamorons of the UK Media , immediately converted
the scientific announcement of a possibility of Earth encounter of 1 in
10,000 , into  "A Direct Hit". But as Brian Marsden of the Harvard
Smithsonian Cantre for AstroPhysics, points out, this kind of stupid
statement is silly for the very good reason that comets are like weak
almost unpredictable rocket engines.
As S-T approaches the Sun at this present encounter, it will get a
roasting. This will melt some of its carbon/ice surface mixture producing
a considerable discharge of gas and dust, which will give the Comet a
rocket like thrust, thereby altering its orbit velocity. So no one can
predict its actual velocity after this pass around the Sun. Anyone who
pretends to be able to predict exactly where S-T will be 124 years after
this present encounter and forecasts a direct hit on the Earth , is either
a media person , or, ( the same thing ), quite crazy. The time to check
S-T will be after it has got a long way from the heat of the Sun say
around 2000 AD. Then telescopes and radar will give a better assessment of
its velocity and hence a better idea of how close it will come in 2116 AD.
It is quite a coincidence that as the arrival of S-T was reported, the
British science magazine Nature was publishing a technical paper, which
seems to almost confirm beyond doubt , that the 200 km diameter sunken
impact crater at Chicxulib in Yucatan Mexico, was indeed contemporary with
the sudden demise of the Dinosaurs and most of the rest of the animal and
plant life then present on the land surfaces of the Earth 65 million years
ago. So we appear to have found a good example of what S-T might do if the
collision odds shorten from the present 10,000 to 1 against to , an odds
on certainty.

You can see Swift-Tuttle as a fuzzy blur in the West North West evening
sky in the constellation of Hercules. But do get away from all town and
house lights and take care you do not mix it up with the beautiful
Globular cluster M13 which is nearby. S-T is tracking from near PI
Hercules on 6 Nov , to pass u Hercules on the 12th Nov. On 29 Nov it will
be at its brightest at Right Ascension 283 degs and Declination 6.5 degs.
Also coming this week peaking 14th Nov, is the midnight to 1400 ut Leonids
shower. This shower has terrific peaks roughly every 33 years. Next big
one is due 1998 or 1999. So this year might see it starting to build up as
its Comet dust stream gets thicker as we approach its 33 year maximum.
73 de GM4IHJ @ GB7SAN