When the Earth's field reverses, new basalt records the reversed direction.

The missile didn't make it before the field reversed.

The earth's field sometimes reverses itself, with the north pole becoming the south and vice versa.

Then, it will begin swirling in the opposite direction and the magnetic field will reverse itself.

A larger opposing field can reverse the reactions in what are called reversible cells.

By making observations such as these, it should be possible to eventually determine why the magnetic field reverses.

The fast strength decrease of the field is a sign that the magnetic field might be reversing.

Scientists over the years have discovered that the planet's magnetic field reverses on average once every 200,000 years or so.

If the magnetic field of the Earth should reverse, the south end would become the south-seeking pole.

They also conducted studies of rocks showing that the earth's magnetic field has reversed a number of times.