22nd June 19:13
The angry Sun: STEREO and Hinode watch explosions in the solar corona (Forwarded)
Royal Astronomical Society
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Dr James Klimchuk
Space Science Division
Naval Research Laboratory
E-mail: jim.klimchuk @ nrl.navy.mil
From 16 to 18 April, Dr Klimchuk can be contacted via the NAM press office
PRESS INFORMATION NOTE: RAS PN 07/10 (NAM 06)
EMBARGOED FOR 00:01 BST, TUESDAY 17 APRIL 2007
THE ANGRY SUN: STEREO AND HINODE WATCH EXPLOSIONS IN THE SOLAR CORONA
Although the Sun is a benevolent provider of warmth and comfort, it also has
a very angry side. Solar outbursts cause inclement space weather that
sometimes wrecks havoc on technological systems on which our society is
progressively more dependent. In a plenary talk on Tuesday 17 April at the
Royal Astronomical Society National Astronomy Meeting in Preston, Dr James
Klimchuk of the Naval Research Laboratory in the USA will present the latest
results from the STEREO and Hinode spacecraft, two missions that have been
studying the Sun for the last few months.
STEREO is a NASA-led mission with substantial participation by scientists
from the UK and other European countries. It consists of two spacecraft
watching the Sun from different vantage points, that will eventually allow
astronomers look at the whole of the region between the Sun and the Earth
for the first time and eventually allow them to construct 3D images of the
Sun. Hinode is a Japanese mission with collaboration from scientists in the
US and UK. It orbits the Earth in a path that gives the probe a continuous
view of the Sun.
One of the key objectives of the two missions is to study solar outbursts.
These involve the sudden release of energy stored in the magnetic fields of
the corona, the hot material that makes up the outer atmosphere of the Sun.
The smallest events or nanoflares heat the corona to a temperature of
millions of degrees and cause the emission of X-ray and ultra-violet
radiation that changes the upper atmosphere of the Earth. The largest
Coronal Mass Ejections (CMEs) are spectacular and can cause storms in the
Earth's magnetic field.
Together, STEREO and Hinode give astronomers the ability to watch CMEs all
the way from the Sun to the Earth. Scientists can watch their evolution as
they interact with the outflow of particles from the Sun (the solar wind)
en-route to our planet. CMEs are the most dramatic 'space weather' events
and can cause damage to technological systems such as power grids and
communication and navigation networks. The severity of the impact of a CME
depends on how it changes as it makes the journey across the inner Solar
system and the new missions allow astronomers to better understand how these
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.
The eruption of a coronal mass ejection (CME) -- a billion tons of
magnetized plasma traveling through space at a million kilometers per hour
-- seen from one of the coronograph instruments on the STEREO mission,
launched 25 October 2006. An occulting disk (black) blocks out the intense
solar surface (indicated by the white circle), much like the Moon does
during a total solar eclipse.
A coronal mass ejection (CME) reaching halfway from the Sun to the Earth,
shown in a composite image from the 5 different telescopes of the SECCHI
instrument package on the STEREO mission. Previous CME observations were
limited to the vicinity of the Sun (square section at left), but we can now
track CMEs all the way to the Earth, where they cause damaging space
weather. The picture is grainy because CMEs are extremely faint far from
the Sun -- a million billion times fainter than the solar surface (a one
followed by 15 zeros)! This is darker than the darkest night sky. Mercury
and Venus can be seen at the bottom left of the image.