PLEASE NOTE:


*

Date sent: Tue, 04 Mar 1997 13:01:36 -0500 (EST)
From: HUMBPEIS <B.J.PEISER@livjm.ac.uk>
Subject: STONEHENGE
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

STONEHENGE BUILT BY BRETONS (NOT BRITONS)?


It's as British as roast beef and Yorkshire pudding, a
concrete symbol of the ancient heritage of a proud island
race. Or is it?

Archaeologist Aubrey Burl claims that Stonehenge,
Britain's top tourist attraction, was designed and built
by Bretons - not by Britons. The enormous stones were not
manhandled into place on Salisbury Plain around 2400 BC
by burly Britons but by visiting Gallic architects.

Dr Burl, who is a former principal lecturer in prehistory
at Hull University, is the author of STONE CIRCLES OF THE
BRITISH ISLES, a catalogue or more than 1,300 such
circles in Britain and Ireland.

His claim that Stonehenge marks a northern outpost of
French culture appears in the current issue of WILTSHIRE
ARCHAEOLOGICAL MAGAZINE.

"The idea gradually fell into place as I studied
Stonehenge and other sites, perhaps helped by a bottle of
Muscadet", Burl told THE EXPRESS (1 March 1997). "Like
everyone else, I had always assumed the builders of
Stonehenge were Britons. But it has several features
alien to Britain which are common in stone circles found
in Brittany".

Other experts remain unconvinced. Julie Gardiner, of
Wessex Archaeology, is quoted by THE EXPRESS as saying:
"If the French had built Stonehenge, I would have thought
there would be some indication of that in objects found
in the area. I can't honestly say that seems to be the
case".

Yet, whoever the original builders of Stonehenge were -
the really interesting question: WHY this and
thousands of other stone circles around the world were
built during the Bronze Age in the first place, remains
unanswered. Hopefully, Duncan Steel will shed some
further light on this problem at Cambridge in July.

Benny Peiser



*

Date sent: Tue, 04 Mar 1997 09:39:33 -0500 (EST)
From: HUMBPEIS <B.J.PEISER@livjm.ac.uk>
Subject: Re: 'ASTEROID' hits National TV
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL

'ASTEROID' - DISASTER MOVIE HITS NATIONAL TV

HOW REALISTIC IS THE STORY?

On Saturday night, GRANADA TV broadcasted the first part
of the American-made movie 'ASTEROID' to a national
audience in the UK. The first part of the disaster movie
describes how astronomers at an US observatory detect two
giant meteorites on collision course with the earth - and
only two days away from impacting. According to the
astronomers, a comet (called Fletcher) is responsible for
this situation because they believe that its gravitational
field changed the asteroids' orbits into earth-crossing
orbits.

Without much hesitation (and only few hours away from
impact), US Air Force pilots are sent to use laser beams
mounted on their fighters in order to 'destroy' both
incoming asteroids. While the smaller one (Helios,
around 1 mile wide) can be successfully exploded and
thus poses no further threat, the bigger asteroid (Eros,
4 miles wide) disintegrates after the laser attack into
thousands of threatening chunks of meteors.

Just when the first part of the movie comes to a close,
this man-made meteor storm is about to impact the earth.
For the sake of the plot (and in order to cater for the
American audience), the astronomers have calculated that
the cosmic bombardement (surprise, surprise) will hit the
State of Texas. (One has to sympathise with the
directors since many prominent US targets have been
already wiped out many times in earlier disaster movies -
so, for instance, the White House by cosmic bombardement
in Independence Day).

I asked Dr Bill Napier of the Armagh Observatory, and one
of Britain's leading experts on cometary astronomy, about
the accuracy of the film's story.

BJP: (1) How realistic is it that observatories would
detect a major astroid on collision course with earth
only two days in advance?

Bill Napier: (1) An impact could easily happen with only
a few days warning; indeed the warning time could be nil
if the asteroid approached from sunwards, i.e on a high
eccentricity, Earth-crossing orbit characteristic of
Taurid Complex asteroids. The 1908 Tunguska impactor, for
example, came in at a low angle from sunwards, i.e.
literally out of the blue!

BJP: (2) How realistic is it that a comet passing the
earth by 1 million miles would attract asteroids into its
gravitational field and thereby change their orbits?

Bill Napier: (2) The gravitational perturbation induced
by even a large comet at a million miles is utterly
negligible compared to that of planets and would not in
any case result in the `entrainment' of asteroids in its
wake.

BJP: (3) How realistic is it that an asteroid 4 miles
wide could be 'destroyed' or (alternatively) deflected
with the currently available technology? Is the idea of
using laser beams more than just science fiction?

Bill Napier: (3) If laser beams mounted on fighters could
pack enough punch to crack up a 4 km rock, they could
also smash mountains here on Earth. I don't think so!
Ground-based lasers might in principle evaporate enough
material off the surface of a near-Earth asteroid to
enable its surface composition to be obtained with
sensitive spectrographs. Current thinking is that a
neutron bomb fired a little way off a rocky asteroid
might evaporate the top few centimetres of surface to
yield a rocket effect, the reaction being enough to nudge
an Earth-approaching asteroid into a safe orbit. However
this is an extremely hairy business which is critically
dependent on modelling assumptions. If, for example, the
asteroid is an inert comet with an internal `rubble pile'
structure such as Shoemaker-Levy 9 seemed to possess,
then you might indeed end up with a shower of fragments
approaching the Earth. In general, any given body might
have a tensile strength between that of shaving foam and
nickel-iron. My own view is that before feasible
deflection strategies can be constructed, we need to know
much more about the internal constitutions of the
Earth-crossers.

BJP: (4) Are astronomers currently able to predict/
calculate the impact area of an incoming cosmic body? And
what about a metor shower? In the movie, the astronomers
are portrayed as calculating Texas as the impact area?
This sounds very odd to me.

Bill Napier: (4) A lot of work has been (and is being)
done on the likely consequences of impacts of various
energies, and there are indeed predictions in the
literature. The SL9 comet was an interesting field trial
and the observed fireball effects broadly confirmed the
theoretical expectations. Localization of intense
meteoroid showers is possible (e.g concentrating on a
continent) and has been observed in some of the great
meteor storms of the past. For fragments formed 2 days
before Earth impact to hit a Texas-sized target,
the separation speed would have to be about 10 metres a
second, or modestly explosive (the destroying lasers
would have had to carry a punch of over 3 megatons,
equivalent to several nuclear warheads).

Finally, you asked for any other comments. It's not
difficult to pick holes in the story (e.g. the assertion
that ocean impacts would be harmless is downright
hilarious if you read the literature). And of course for
the same money the scriptwriters could have gotten
the science right and still had a dramatic bolide shower:
see the prologue of The Cosmic Winter by Victor Clube and
myself. Further, the damage done by a fragmented 4-mile
asteroid would be orders of magnitude more horrendous
than is portrayed in the mini-series (at least Part I;
I haven't seen Part II). However my general feeling is
that if ASTEROID raises public awareness of the celestial
hazard issue, then it will have performed a service over
and above whatever entertainment value it may have.

------------------------------------

The last episode of ASTEROID will be shown next Saturday
night on GRANADA. I will try to keep you up to date.

Further information and comments on this highly complex
but increasingly 'publicised' issue by other
astronomers on this network would be much appreciated.



CCCMENU CCC for 1997

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of

The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.