Posted on 12/03/2003 6:44:42 PM PST by NormsRevenge
WASHINGTON (Reuters) - The solar wind pries open immense cracks in the Earth's magnetic field, holding them apart while it gushes through to cause geomagnetic storms, scientists reported on Wednesday.
The findings could help scientists better predict the storms, which can disrupt power, satellites and communications and endanger astronauts, the U.S. space agency NASA (news - web sites) said.
"We think we have solved an old and long-standing controversial discussion of how this process of crack formation really works," Harald Frey of the University of California, Berkeley, who led the study, told a news conference.
"Now that we know these cracks do not just open and close sporadically ... but can stay open for a long and extended time of several hours ... we can go on and incorporate this knowledge into our next step of modeling space weather impacts."
The findings, published in this week's issue of the journal Nature, were made using the orbiting IMAGE satellite, designed to watch the Earth's protective magnetic layer or magnetosphere. A group of four satellites called Cluster detected the charged solar particles streaming through.
"It is critical for us to understand where, when, and for how long the magnetic shield is breached and how this energy gets in," said Janet Kozyra of the University of Michigan, a space weather expert who did not work on the study.
This information "will help us to make more accurate space weather predictions."
The Sun regularly spews out charged gas called plasma in what is known as a coronal mass ejection. "Our magnetic shield takes the brunt of space storms, but some energy continually slips through its cracks, sometimes enough to cause problems with satellites, radio communication, and power systems," Frey said.
"The only things that humans can really see in a magnetic storm are the aurora lights," Kozyra added.
The space storms can dump 1,000 billion watts into the atmosphere while they last -- more than the total electric generating capacity of the United States.
IMAGE -- the Imager for Magnetopause to Aurora Global Exploration -- revealed an area of heavy particles called ions almost the size of California hitting the ionosphere above the Arctic region.
"This aurora, energetic enough to power 75,000 homes, was different from the visible aurora known as the Northern and Southern lights," NASA said in a statement.
"While the aurora was being recorded by IMAGE, the 4-satellite Cluster constellation flew far above IMAGE, directly through the crack, and detected solar wind ions streaming through. Normally, these solar wind ions would be deflected by Earth's shield, so Cluster's observation showed a crack was present."
The researchers estimated the crack was twice the size of the Earth at a point 38,000 miles above the planet's surface. Such cracks evidently open all the time, said Nancy Crooker of Boston University.
Several monster solar storms hit the Earth last month but caused little disruption. When officials know they are coming they can move satellites and prepare power grids to minimize the effects.
Earth's Magnetic Field Stands Off the Solar Wind
An unseen struggle rages in space near the Earth. The million miles per hour solar wind, a gas comprised primarily of electrons and protons, relentlessly streams toward our planet. It is held at bay by the Earth’s vast magnetic field, which deforms under the onslaught of this solar gale, like a jellyfish buffeted by water currents, or a large tent flapping in a desert wind storm.
The solar wind compresses the Earth’s magnetic field to about 40,000 miles (64,374 kilometers) from Earth on Earth’s dayside, and stretches it to about 800,000 miles (1,280,000 kilometers) on the night side. This volume of space containing the Earth’s magnetic field is known as the magnetosphere. Once solar wind particles have penetrated the magnetosphere, they are guided by the Earth’s magnetic field.
The electrically charged particles of the solar wind infiltrate the Earth’s magnetic realm with an intensity and impact that depends on solar conditions and the direction of the magnetic field carried by the solar wind. Electrons and protons spiral down a funnel-like region of the magnetic field above Earth’s day-side polar regions (a structure called the polar cusp) and hit the upper atmosphere, eventually creating the haunting glow that are the northern and southern lights. At the same time, these particles generate electrical currents that distort Earth’s magnetic field, especially at high northern and southern latitudes. The most severe disruptions of the magnetic field are known as geomagnetic storms, and these electric currents and energetic particles occasionally disable satellites, radio communications, and power systems.
This interaction is very complex and researchers do not understand all the effects of the solar wind on the Earth. The magnetosphere’s enormous size and complexity makes it impossible to understand with isolated spacecraft. A fleet of four identical spacecraft, called Cluster II, will explore portions of this turbulent region beginning in the summer of 2000.
Cluster II
During its two-year mission, the quartet of satellites will travel around Earth collecting data where the solar wind impacts Earth's magnetic field. The first Cluster pair, called Samba and Salsa, launched July 2000. The second pair, called Rumba and Tango, launched August 2000.
The Cluster II mission consists of four similar spacecraft and is part of ESA's and NASA's Solar-Terrestrial Science Program (STSP). The purpose of the mission is to study small-scale structures in three dimensions in the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids.
Plumbers to blame.
Solar wind and other space weather related info for dummies and stuff.
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I posted an illustrated version of this article at today's APOD.
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