Last weekend’s skies lit up with a stunning display of the aurora borealis, visible as far south as Alabama, thanks to a powerful coronal mass ejection. This celestial phenomenon, typically confined to polar regions, underscores the dramatic effects that solar activities can have on Earth. Coronal mass ejections are not only beautiful but also bear …
Continue reading “Impacts and insights on coronal mass ejections”
The magnetic field radiates around the Earth and far into space, but it is set by processes that happen deep within its core, where temperatures exceed 5,000 degrees Celsius.
One of the key tenets of geophysics is that Earth’s liquid outer core has always been the source of the dynamo that generates its magnetic field. Magnetic fields form on Earth and other planets that have liquid, metallic cores, rotate rapidly and maintain conditions that make the convection of heat possible.
A team led by Alan Cooper found a detailed record of the Laschamp excursion about 41,000 years ago from the rings of New Zealand swamp kauri trees. The record reveals a substantial increase in the carbon-14 content of the atmosphere during the period of weakening magnetic field strength preceding the polarity switch.
During the past 50 years, field measurements of sea-floor magnetic anomalies combined with paleomagnetic studies of volcanic and sedimentary sequences have yielded the construction of the geomagnetic polarity time scale. Excursions represent periods during which the magnetic pole deviates by more than 40° away from the geographic pole.
The earth has a large-scale dipolar magnetic field. The magnetic North and South poles are commonly understood as positions on the Earth where the geomagnetic field is vertical (i.e., perpendicular) to the ellipsoid. The Earth’s magnetic field shields us against high-energy particles from the Sun and outer space, thereby protecting our atmosphere and the life …
