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11-02-2008, 01:19 AM | #1 |
Avalon Senior Member
Join Date: Sep 2008
Location: Third Planet of our solar system
Posts: 104
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NASA - Magnetic Portals Connect Sun and Earth
http://science.nasa.gov/headlines/y2...htm?list749571
Magnetic Portals Connect Sun and Earth 10.30.2008 Oct. 30, 2008: During the time it takes you to read this article, something will happen high overhead that until recently many scientists didn't believe in. A magnetic portal will open, linking Earth to the sun 93 million miles away. Tons of high-energy particles may flow through the opening before it closes again, around the time you reach the end of the page. "It's called a flux transfer event or 'FTE,'" says space physicist David Sibeck of the Goddard Space Flight Center. "Ten years ago I was pretty sure they didn't exist, but now the evidence is incontrovertible." Indeed, today Sibeck is telling an international assembly of space physicists at the 2008 Plasma Workshop in Huntsville, Alabama, that FTEs are not just common, but possibly twice as common as anyone had ever imagined. Right: An artist's concept of Earth's magnetic field connecting to the sun's--a.k.a. a "flux transfer event"--with a spacecraft on hand to measure particles and fields. [Larger image] Researchers have long known that the Earth and sun must be connected. Earth's magnetosphere (the magnetic bubble that surrounds our planet) is filled with particles from the sun that arrive via the solar wind and penetrate the planet's magnetic defenses. They enter by following magnetic field lines that can be traced from terra firma all the way back to the sun's atmosphere. Sign up for EXPRESS SCIENCE NEWS delivery "We used to think the connection was permanent and that solar wind could trickle into the near-Earth environment anytime the wind was active," says Sibeck. "We were wrong. The connections are not steady at all. They are often brief, bursty and very dynamic." Several speakers at the Workshop have outlined how FTEs form: On the dayside of Earth (the side closest to the sun), Earth's magnetic field presses against the sun's magnetic field. Approximately every eight minutes, the two fields briefly merge or "reconnect," forming a portal through which particles can flow. The portal takes the form of a magnetic cylinder about as wide as Earth. The European Space Agency's fleet of four Cluster spacecraft and NASA's five THEMIS probes have flown through and surrounded these cylinders, measuring their dimensions and sensing the particles that shoot through. "They're real," says Sibeck. Now that Cluster and THEMIS have directly sampled FTEs, theorists can use those measurements to simulate FTEs in their computers and predict how they might behave. Space physicist Jimmy Raeder of the University of New Hampshire presented one such simulation at the Workshop. He told his colleagues that the cylindrical portals tend to form above Earth's equator and then roll over Earth's winter pole. In December, FTEs roll over the north pole; in July they roll over the south pole. Right: A "magnetic portal" or FTE mapped in cross-section by NASA's fleet of THEMIS spacecraft. [Larger image] Sibeck believes this is happening twice as often as previously thought. "I think there are two varieties of FTEs: active and passive." Active FTEs are magnetic cylinders that allow particles to flow through rather easily; they are important conduits of energy for Earth's magnetosphere. Passive FTEs are magnetic cylinders that offer more resistance; their internal structure does not admit such an easy flow of particles and fields. (For experts: Active FTEs form at equatorial latitudes when the IMF tips south; passive FTEs form at higher latitudes when the IMF tips north.) Sibeck has calculated the properties of passive FTEs and he is encouraging his colleagues to hunt for signs of them in data from THEMIS and Cluster. "Passive FTEs may not be very important, but until we know more about them we can't be sure." There are many unanswered questions: Why do the portals form every 8 minutes? How do magnetic fields inside the cylinder twist and coil? "We're doing some heavy thinking about this at the Workshop," says Sibeck. Meanwhile, high above your head, a new portal is opening, connecting your planet to the sun. SEND THIS STORY TO A FRIEND Author: Dr. Tony Phillips | Credit: Science@NASA more information 2008 Huntsville Plasma Workshop -- home page Below: In a presentation at the 2008 Plasma Workshop, Robert Fear of the University of Leicester, UK, presented some alternatives for the magnetic topology of FTEs. Possibilities include ropes (left column), cylinders (middle column), or bubbles (right column): abstract. NASA's Future: US Space Exploration Policy USAGov + Freedom of Information Act + Budgets, Strategic Plans and Accountability Reports + The President’s Management Agenda + Privacy Policy and Important Notices + Inspector General Hotline + Equal Employment Opportunity Data Posted Pursuant to the No Fear Act + Information-Dissemination Priorities and Inventories + USA.gov - Your First Click to the US Government + ExpectMore - A Program Which Determines Whether Government Programs Are Effective NASA Curator: Bryan Walls NASA Official: John M. Horack Last Updated: June 9, 2005 + Contact NASA Last edited by Adarajones; 02-09-2009 at 02:51 AM. |
11-02-2008, 01:28 AM | #2 |
Avalon Senior Member
Join Date: Oct 2008
Posts: 97
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Re: NASA - Magnetic Portals Connect Sun and Earth
Thanks!
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11-02-2008, 01:29 AM | #3 |
Avalon Senior Member
Join Date: Sep 2008
Posts: 1,098
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Re: NASA - Magnetic Portals Connect Sun and Earth
Hi Adara, already posted here... http://projectavalon.net/forum/showthread.php?t=6515
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