PLEASE NOTE:


*

ROYAL ASTRONOMICAL SOCIETY
PRESS INFORMATION NOTE

Date: 8 December 1998

Ref. PN 98/28

Issued by:

Peter Bond,
RAS Space Science Advisor.
10 Harrier Close,
Cranleigh,
Surrey, GU6 7BS,
United Kingdom.
Phone: +44 (0)1483-268672
Fax: +44 (0)1483-274047
E-mail: 100604.1111@compuserve.com

DEFINING THE EFFECTS OF SUB-CRITICAL COSMIC IMPACTS ON THE EARTH.

DISCUSSION MEETING AT GEOLOGICAL SOCIETY, BURLINGTON HOUSE, PICCADILLY,
LONDON W1.

"Sub-Critical Scale Impactors" i.e. near-Earth asteroids and small
comets, will be the subject of a one-day discussion meeting in London
on Friday December 11th as part of the Royal Astronomical Society's
regular monthly programme. Media representatives are cordially invited
to attend as observers.

The symposium brings together leading UK and French scientists to
discuss the probability of such impacts, the different environmental
and biological effects they create, and the known impact record on
Earth. 

Impacts have defined the evolution of life throughout the Earth’s
history. At least one significant impact-related event has occurred in
recent history, the explosion of a comet or asteroid over Tunguska in
Siberia in 1908. There is no reason why a similar event could not
eventually happen,  through an accident of geometry and time, over
London, Paris or New York.

Whilst a large impact could result in global devastation, the
likelihood of Earth being struck by objects 10 km (6 miles) across is
extremely remote - perhaps once every 50 million to 100 million years.
On the other hand, much smaller, Tunguska-like events are expected to
occur, on average, once every 50-100 years. Although these sub-critical
impacts do not threaten large-scale extinctions, they are still likely
to have significant  effects on the surrounding environment. For
example, it is now realised that the environmental effects of a SCI
vary greatly depending on where the impactor lands.

The speakers at the symposium will discuss the hazard presented by
these sub-critical impacts (SCIs) and the likely consequences for
Earth’s climate and biosphere. In recent years this subject has
developed into an important scientific discipline. The significance of
comets and asteroids in the formation of the Earth, as well as the
origin and evolution of life, has been increasingly recognised.
According to one theory, most of Earth’s water was delivered by comets
and flavoured with the building blocks of life brought  by both
asteroids and comets. However, only in the past few years has the
reality and magnitude of the hazard presented by these objects been
appreciated as evidence has been accumulated supporting the theory that
a major impact 65 million years ago ended the rule of the dinosaurs and
paved the away for the emergence of the mammals.

The meeting has been organised by Richard Taylor, David Hughes, and
Julian Hiscox, under the auspices of the Royal Astronomical Society and
the British Interplanetary Society (BIS).

An outline of the programme, and contact details for the organisers is
given below. For further information on individual contributions,
please contact the meeting organisers.
###

RAS/BIS/GS Joint Discussion meeting at the
GEOLOGICAL SOCIETY LECTURE THEATRE
BURLINGTON HOUSE, PICCADILLY, LONDON W1

FRIDAY 11th DECEMBER 1998

Organisers:
Dr. David Hughes, Dept. of Physics, University of Sheffield, Sheffield
S3 7RH. Tel: +44 (0)114-222-4288. Fax: +44 (0)114-272-8079
E-mail: d.hughes@sheffield.ac.uk

Dr. Julian Hiscox, IAH Compton Laboratory, Compton, Berkshire RG20 7NN.
Tel: +44 (0)1635-577274. Fax: +44 (0)1635-577263
E-mail: julian.hiscox@bbsrc.ac.uk

Richard Taylor, Probability Research Group, 4 Abingdon Road, Norbury,
London SW16 5QP. Tel: +44 (0)181-764-2774.
E-mail:  richard.taylor3@virgin.net
       
PROGRAMME AND SPEAKERS.

FIRST SESSION - The Nature and Frequency of Small Impactors.
Chairman: Dr. Julian Hiscox.

10:30  Dr. Matthew Genge (Natural History Museum)
The implications of meteorites and micrometeorites for the nature of
sub-critical impactors.

10:45  Mr. Jonathan Tate (Spaceguard UK)
The frequency of SCI impactors with diameters in the 0.1 to 1km range

11:00  Dr. David Hughes (University of Sheffield)
The cratering rate of planet Earth.

SECOND SESSION - Geological and Climatic Evidence.
Chairman: Dr. David Hughes.

11:15   Professor Ian Smalley & Mr. Ian Jefferson (Nottingham Trent
          University)
Sedimentological consequences of sub-critical impacts in sandy deserts
or loess regions.

11:30   Professor Nicholas Fedoroff - (Institut National Agronomique,
          France)
Registration of abrupt events in loess: around 67000 yrs BP (before
present)transition reveals unusual attributes.

11:50   Professor Claudio Vita-Finzi (University College, London)
Seasonal enhancement and seismic triggering by impacts

12:05   Professor Chandra Wickramasinghe, M.K. Wallis and D.H. Wallis
          (University of Wales, College of Cardiff)
Climatic Switches Induced by Stratospheric Dust Loading.

12:20   Discussion.

12:35   LUNCH

THIRD SESSION - Evidence for Evolutionary and Recent Environmental
Effects. Chairman: Professor Ian Smalley.

1:35    Dr. Norman MacLeod (Natural History Museum, London)
Identifying instances of past environmental change and their causal
mechanisms.

1:55    Dr. Julian Hiscox (IAH Compton Laboratory)
Possible biochemical/bioevolutionary consequences of SCI events.

2:10    Dr. Marie-Agnes Courty (National Centre for Scientific 
          Research, France)
Recognition of instantaneous soil collapse at 3950 BP (before present)
throughout the Middle East in response to a blast wave, wild fires and
heavy rains caused by an extra-terrestrial event.

2:30    Dr. Benny Peiser (Liverpool John Moores University)
Current research on Holocene impact events and its implications for
impact rate calculations.

2:50    Dr. Victor Clube (Oxford University and Armagh Observatory)
Sub-cometary and sub-asteroidal impacts: historical considerations.

FOURTH SESSION - Wider Implications of Impacts.
Chairman: Professor Claudio Vita-Finzi.

3:10    Professor Neville Price (formerly University College, London)
Evidence for impact as a significant and periodic geological process.

3:25    Close.



CCCMENU CCC for 1998

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.