First Measurement of Magnetic Field In Earth's Core 34
An anonymous reader writes "A University of California, Berkeley, geophysicist has made the first-ever measurement of the strength of the magnetic field inside Earth's core, 1,800 miles underground. The magnetic field strength is 25 Gauss, or 50 times stronger than the magnetic field at the surface that makes compass needles align north-south. Though this number is in the middle of the range geophysicists predict, it puts constraints on the identity of the heat sources in the core that keep the internal dynamo running to maintain this magnetic field."
Re:So, is our goose cooked? (Score:5, Insightful)
In a thousand years or so, fossil fuels will be gone. In a hundred thousand years the biosphere will be totally run down by human exploitation, unless we manage it end to end as a farm. In a billion years (or so) the suns output will have changed to move the habitable zone away from the Earth. In five billion years the sun will become a red giant and we will all be toast.
I don't know when we will lose the magnetic field but if it happens anywhere after a thousand years from now we should be able to build our own. If we can't then we are not much of an intelligent species and we will be heading for extinction anyway.
Re:Measurement? What measurement? (Score:5, Insightful)
Can you name any measurement that isn't indirect in some way? To measure a magnetic field, you're actually observing something that the field affects such as a Hall effect magnetometer which measures the voltage potential induced by a magnetic field in a conductor or a SQUID magnetometer which measures a current accross a josephson junction