the quiet before a storm - the
most intense solar maximum in fifty years"
geomagnetic storm is a temporary disturbance of the Earth's
magnetosphere caused by a disturbance in space weather.
solar coronal mass ejections (CME), coronal holes, or solar flares, a
geomagnetic storm is caused by a solar wind shock wave which typically
strikes the Earth's magnetic field 8 days after the event.
only happens if the shock wave travels in a direction toward Earth. The
solar wind pressure on the magnetosphere will increase or decrease
depending on the Sun's activity.
solar wind pressure changes modify the electric currents in the
ionosphere. Magnetic storms usually last 24 to 48 hours, but some may
last for many days.
In 1989, an electromagnetic storm disrupted power
throughout most of Quebec, Canada and caused auroras as far south as
Scientists are beginning to understand a historic solar storm in 1859. One day, they say, it could happen again.
The solar wind also carries with it the magnetic field of the Sun. This field will have either a North or South orientation.
the solar wind has energetic bursts, contracting and expanding the
magnetosphere, or if the solar wind takes a southward polarization,
geomagnetic storms can be expected.
southward field causes magnetic reconnection of the dayside
magnetopause, rapidly injecting magnetic and particle energy into the
a geomagnetic storm, the ionosphere's F2 layer will become unstable,
fragment, and may even disappear. In the northern and southern pole
regions of the Earth, auroras will be observable in the sky.
solar flares release very-high-energy particles that can cause
radiation poisoning to humans (and mammals in general) in the same way
as low-energy radiation from nuclear blasts.
atmosphere and magnetosphere allow adequate protection at ground level,
but astronauts in space are subject to potentially lethal doses of
The penetration of high-energy particles into living cells
can cause chromosome damage, cancer, and a host of other health
problems. Large doses can be fatal immediately.
protons with energies greater than 30 MeV are particularly hazardous.
In October 1989, the Sun produced enough energetic particles that, if an
astronaut were to have been standing on the Moon at the time, wearing
only a space suit and caught out in the brunt of the storm, would
probably have died; the expected dose would be about 7000 rem.
that Astronauts who had time to gain safety in a shelter beneath moon
soil would have absorbed only slight amounts of radiation.
Newly uncovered scientific
data of recorded history's most massive space storm is helping
a NASA scientist investigate its intensity and the probability
that what occurred on Earth and in the heavens almost a
ago could happen again.
cosmonauts on the Mir station were subjected to daily doses of about
twice the yearly dose on the ground, and during the solar storm at the
end of 1989 they absorbed their full-year radiation dose limit in just a
Solar proton events can also produce elevated radiation
aboard aircraft flying at high altitudes.
these risks are small, monitoring of solar proton events by satellite
instrumentation allows the occasional exposure to be monitored and
evaluated, and eventually the flight paths and altitudes adjusted in
order to lower the absorbed dose of the flight crews.