What is a geomagnetic reversal?
Q: What is a geomagnetic reversal?
A: A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.
Q: How often do these reversals occur?
A: Reversals occur approximately two or three times per million years, with intervals ranging from less than 0.1 million years to as much as 50 million years.
Q: How long does it take for a reversal to happen?
A: Most reversals take between 1,000 and 10,000 years to happen. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago; and may have happened very quickly, within a human lifetime.
Q: What is an example of a brief complete reversal?
A: A brief complete reversal known as the Laschamp event occurred only 41,000 years ago during the last glacial period. That reversal lasted only about 440 years with the actual change of polarity lasting around 250 years.
Q: How weak was the Earth's magnetic field during this change?
A: During this change the strength of the magnetic field weakened to 5% of its present strength.
Q: What are chrons?
A: Chrons are periods which range from 0.1 to 1 million year intervals with an average of 450,000 year intervals between them when reversals occur at random without any pattern or regularity.
Q: What are geomagnetic excursions?
A: Geomagnetic excursions are brief disruptions that do not result in full reversals but still cause changes in the Earth's magnetism
