ROYAL ASTRONOMICAL SOCIETY PRESS INFORMATION NOTE

Issued by RAS Press Officers:

Dr Robert Massey
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Anita Heward
Tel: +44 (0)1483 420904

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Tel: +44 (0)2890 975262 / 975263 / 975264

NAM 2008
http://nam2008.qub.ac.uk

Royal Astronomical Society
http://www.ras.org.uk

CONTACT

Professor Fred W Taylor
Halley Professor of Physics
Fellow of Jesus College
University of Oxford
Clarendon Laboratory
Parks Road
Oxford OX1 3PU
Tel: +44 (0) 1865 272933
Fax: +44 (0)1865 272923

EMBARGOED UNTIL 0001 BST, 2 April 2008

Ref.: PN 08/22 (NAM 13)

The evolution of Venus: first too fast, then too slow

Scientists analysing the data from the European Venus Express spacecraft now
orbiting Earth's prodigal twin planet have been piecing together an
understanding of why the climate on both worlds is so different. Professor
Fred Taylor of Oxford University will present the scenario in a talk at the
RAS National Astronomy Meeting in Belfast on Wednesday 2nd April.

In the early stages of the Solar System, Venus seems to have evolved very
rapidly compared to the Earth. Data from Venus Express supports the theory
that the Earth's twin once had significant volume of water covering the
surface but it appears that these oceans were lost in a very short
geological timescale. As a result of the loss of water, the geological
evolution of the surface of Venus slowed right down because it was unable to
develop plate tectonics like the Earth. Biological evolution was prevented
altogether. Thus, in terms of Venus being another Earth in climate and
habitability terms, it evolved too quickly at first, then too slowly.

"They may have started out looking very much the same," said Professor
Taylor, "but increasingly we have evidence that Venus lost most of its water
and Earth lost most of its atmospheric carbon dioxide."

Here, the CO2 is locked up in minerals in the crust, in the oceans, and in
plant life. The release of some of this back into the atmosphere is the
source of current concern about global warming and climate change. On Venus,
most of the CO2 is still in the atmosphere and the surface temperature is a
scorching 450 degrees Celsius, slowing or stopping geological as well as
biological evolution. It is much too hot for life as we know it, for
instance.

"The interesting thing is that the physics is the same in both cases," said
Prof Taylor. "The great achievement of Venus Express is that it is putting
the climatic behaviour of both planets into a common framework of
understanding."

The job is not finished yet -- Venus Express is currently due to operate
until May 2009, and the scientists involved are busy applying for an
extension until 2011.

"We have plans for joint operations with the Japanese spacecraft called
Venus Climate Orbiter that will arrive in December 2010," said Taylor.
"Together, we can do things neither could do alone to crack some of the
remaining puzzles about Venus."

IMAGES
http://www.ras.org.uk/images/stories/press/NAM08/Venus.jpg

Caption: General view from below the south pole of weather on Venus. Image
obtained by the Venus Monitoring Camera. ESA/ MPS/DLR/IDA.

Further images of Venus and Venus Express can be found at:
     http://www.esa.int/esaMI/Venus_Express/index.html

NOTES FOR EDITORS

RAS NATIONAL ASTRONOMY MEETING

The RAS National Astronomy Meeting (NAM 2008) is hosted by Queen's
University Belfast. It is principally sponsored by the RAS and the STFC. NAM
2008 is being held together with the UK Solar Physics (UKSP) and
Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring meetings.

VENUS EXPRESS

The European Space Agency's Venus Express spacecraft has been orbiting Venus
since April 2006. Its mission is to study the Venusian atmosphere and clouds
in unprecedented detail and accuracy. For details, see:
     http://www.esa.int/esaMI/Venus_Express/index.html
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