STEREO gives astronomers a first look at the space between the Earth and Sun (Forwarded)

Royal Astronomical Society
London, U.K.

Issued by RAS Press Officers:

Robert Massey
Tel: +44 (0)20 7734 4582
AND
Anita Heward
Tel: +44 (0)1483 420 904

NATIONAL ASTRONOMY MEETING PRESS ROOM (16 - 20 APRIL ONLY):
Tel: +44 (0)1772 892 613
+44 (0)1772 892 475
+44 (0)1772 892 477

RAS Web site:
http://www.ras.org.uk/

RAS National Astronomy Meeting web site:
http://nam2007.uclan.ac.uk

CONTACTS:

Professor Richard Harrison, Rutherford Appleton Laboratory
HI/STEREO Principal Investigator
Tel: +44 (0)1235 446884
Mob: +44 (0)7876 582 776

Dr Chris Davis, Rutherford Appleton Laboratory
HI/STEREO Project Scientist
Tel: +44 (0)1235 446710

From 16-20 April, the STEREO team can be contacted via the RAS press
office (details above).

PRESS INFORMATION NOTE: RAS PN 07/11 (NAM07)

EMBARGOED FOR 00:01 BST, TUESDAY 17 APRIL 2007

STEREO GIVES ASTRONOMERS A FIRST LOOK AT THE SPACE BETWEEN THE EARTH AND
SUN

For the first time, an international team of astronomers have a side-on
view as giant clouds of solar material leave the Sun and slam into the
magnetic field of the Earth. On Tuesday 17 and Wednesday 18 April at the
RAS National Astronomy Meeting in Preston, Professor Richard Harrison and
Dr Chris Davis of the Rutherford Appleton Laboratory will present
spectacular images and movies of these dramatic events taken by UK cameras
mounted on the two STEREO spacecraft.

The two spacecraft that make up the NASA STEREO mission were launched last
October. One probe is now travelling in an orbit ahead of the Earth while
the other lags behind. Together the probes are imaging the Sun in 3D. They
also have a unique perspective -- they can view the space between the Sun
and the Earth (the so-called Earth-Sun line), giving scientists their
first views of this region of space.

The Rutherford Appleton Laboratory (RAL) in Oxfordshire and the University
of Birmingham led an international effort to develop two identical
Heliospheric Imager (HI) instruments. One HI is mounted on each of the two
spacecraft so astronomers can watch the Earth-Sun line. In particular,
this view gives scientists a ringside seat when giant clouds of material
(Coronal Mass Ejections or CMEs) travel from the Sun to the Earth.

CMEs can be made up of more than 1000 million tonnes of charged particles
and travel at up to 1000 km per second. When a CME reaches the Earth it
can have dramatic effects; compressing the terrestrial magnetic field,
generating displays of the northern lights, disrupting radio
communications, overloading power grids and damaging satellites.

The ability to track CMEs as they leave the Sun, to understand how they
propagate and evolve and to predict their arrival at Earth are all goals
of the unique HI system. As the STEREO spacecraft move into their orbits
over the coming months we will see increasingly better views of the 3D Sun
and the passage of Earth-directed clouds in space. However, the UK HI
instruments have now made their first observations of CMEs in the inner
solar system, showing spectacular images of these clouds and demonstrating
that the instruments are operating flawlessly.

NOTES FOR EDITORS

The 2007 RAS National Astronomy Meeting is hosted by the University of
Central Lancashire. It is sponsored by the Royal Astronomical Society and
the UK Science and Technology Facilities Council.

This year the NAM is being held together with the UK Solar Physics (UKSP)
and Magnetosphere, Ionosphere and Solar-Terrestrial (MIST) spring
meetings. 2007 is International Heliophysical Year.

STEREO is a NASA-led mission, with major contributions from European
countries including the UK.

Further information can be found at
http://www.stereo.rl.ac.uk

The HI images are on the RAL STEREO site at
http://www.stereo.rl.ac.uk/STEREO_Gallery.html

IMAGE CAPTION:
[http://www.nam2007.uclan.ac.uk/press/images/20070417b1.png (148KB)
and
http://www.nam2007.uclan.ac.uk/press/images/20070417b2.mpg (648KB)]
A solar mass ejection viewed in the inner solar system from one of the UK
HI instruments on STEREO. The Sun is off the right hand side and the Earth
is off the left hand side of the image. We see a background of stars as
well as the two inner planets (the brightest objects in the frame) Venus
(left) and Mercury (right). The cloud of solar material can be seen
entering the frame from the right, setting off on its journey from the Sun
to the Earth.

More images and animations of Coronal Mass Ejections can be found at
http://solar.bnsc.rl.ac.uk

Images of and from the STEREO spacecraft can be found at
http://stereo.gsfc.nasa.gov


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