samvado
20th April 2010, 17:25
I thought I inject a bit of science into the discussion
neither.
However, it will change the way we use a compass needle.
Magnetic reversals do occur. On average every 700,000 years... and we are due.
A reversal (once it has started... and it has not yet started) takes about 5,000 years to happen on average -- the fastest ones being over in a mere 1,000 years.
Some of the signs are
-rapid movement -- relatively speaking -- of the locations of magnetic poles,
-splitting of the locations of the magnetic poles
-rapid changes (and weakening) of the field strength
[and many more]
The Earth's magnetism is generated very deep (around the outer core, below the inner mantle). What we call a "magnetic pole" is simply the location(s), on Earth's surface, where the orientation of the field is vertical.
Over the last decade, the north magnetic pole has been moving quite a bit (relatively speaking).
A few decades ago, the south magnetic pole was split (there were two separate location where the field was perpendicular to the surface).
However, when I was studying magnetism a few decades ago, the reversal had not begun (we were "betting" on the 35th century).
Even if it had begun, it will take at least a thousand years. The Earth's field does NOT disappear during the change and we continue to be protected from charged cosmic particles (and solar wind).
It's just that the shape of the field will be very difficult to model. Pity the geophysics students planning to graduate in 3486.
neither.
However, it will change the way we use a compass needle.
Magnetic reversals do occur. On average every 700,000 years... and we are due.
A reversal (once it has started... and it has not yet started) takes about 5,000 years to happen on average -- the fastest ones being over in a mere 1,000 years.
Some of the signs are
-rapid movement -- relatively speaking -- of the locations of magnetic poles,
-splitting of the locations of the magnetic poles
-rapid changes (and weakening) of the field strength
[and many more]
The Earth's magnetism is generated very deep (around the outer core, below the inner mantle). What we call a "magnetic pole" is simply the location(s), on Earth's surface, where the orientation of the field is vertical.
Over the last decade, the north magnetic pole has been moving quite a bit (relatively speaking).
A few decades ago, the south magnetic pole was split (there were two separate location where the field was perpendicular to the surface).
However, when I was studying magnetism a few decades ago, the reversal had not begun (we were "betting" on the 35th century).
Even if it had begun, it will take at least a thousand years. The Earth's field does NOT disappear during the change and we continue to be protected from charged cosmic particles (and solar wind).
It's just that the shape of the field will be very difficult to model. Pity the geophysics students planning to graduate in 3486.