Earth loses its magnetism
By Molly Bentley
in San Francisco
Scientists have known for some time that the Earth's magnetic field is fading.
The field is mainly dipolar - but there are anomalies
Like a Kryptonite-challenged Superman, its strength has steadily and mysteriously waned, leaving parts of the planet vulnerable to increased radiation from space.
Some satellites already feel the effects.
What is uncertain is whether the weakened field is on the way to a complete collapse and a reversal that would flip the North and South Poles.
Compasses pointing North would then point South.
The only thing stopping Earth having a lifeless environment like Mars is the magnetic field that shields us from deadly solar radiation and helps some animals migrate, and it may be a lot more fragile and febrile than one might think.
Scientists say earth's magnetic field is weakening and could all but disappear in as little as 500 years as a precursor to flipping upside down.
It has happened before - the geological record suggests the magnetic field has reversed every 250,000 years, meaning that, with the last event 800,000 years ago, another would seem to be overdue.