THE SAINTLY SUN
What would you think if I told you that there is a huge explosion of
gas from the Sun going to hit the Earth. The end of the world or just
science fiction? Well, it happens all the time because some of the
CMEs from the Sun do come toward the Earth.
How do we recognise them? As they come out from the Sun they show up
as a bright ring in LASCO pictures. Because of their shape they are
called halo CMEs.
Image courtesy of the LASCO/SOHO consortium. SOHO is a mission of international cooperation between of ESA and NASA.
This is a picture of a halo CME seen by LASCO on 7th April 1997. The
bright ring is gas that is coming towards the Earth. The bright object
at the bottom underneath the LASCO logo is the planet Venus.
CMEs travel so fast through space that it only takes three to four days
for them to reach the Earth.
Over 200 years!
Be warned! CMEs can be harmful...
CMEs can mean bad news for us on Earth. They carry a lot of
charged particles (
ions
) which disrupt radio communications and can
cause electricity blackouts, especially near the north magnetic pole
which is in Canada.
They can also destroy satellites and could be harmful to astronauts in
space. As well as seeing CMEs LASCO can also detect very fast
particles that come from solar flares which also cause a lot of
disruption to satellites. All the white specks in the image below are caused by
particles (rather than radiation) from the Sun hitting the camera.
Image courtesy of the LASCO/SOHO consortium. SOHO is a mission of international cooperation between of ESA and NASA.
Have a look at this movie to see a "snowstorm" seen by LASCO
A 2-day snowstorm in space
(QuickTime, 471Kb).
So you see, it's important that we know when large CMEs are going to
hit. LASCO gives us good warning! We are now trying to use data from
LASCO and other satellites to make space weather forecasts. This would
help the people who run satellites. If they know when the
space weather will be bad they can prevent damage to their satellites
by shutting them down until the storm has passed!
...but CMEs can also produce nice effects too.
The Earth is like a giant bar magnet which means it has a magnetic
north and south pole. At these poles CME particles can break through
the Earth's magnetic field and enter the atmosphere where they make
beautiful colorful displays in the sky called aurora. These aurora are
at their best when the Sun is very active and the space weather is
particularly bad!
This is an illustration of the effect the Sun can
have on the Earth.
The Earth is shielded by a protective layer,
but particles from the Sun can creep through in
the polar regions, causing aurorae.
See Andy Breen's adventure for more information on aurorae.
