When geophysicist Andrew Jackson was poring over 17th-century observations of Earth's magnetic field, perhaps the last thing he expected to discover was a new potential extinction date for the dodo, the goofy-looking, flightless bird that became a poster child of extinct species.
The Earth's magnetic field, created by molten iron in the outer core, is the protective envelope around the planet that guards the surface against bursts of solar radiation; without it, life as we know it would cease to exist. Studying the ancient magnetic field of the planet helps scientists to better understand the present-day magnetic field and how it will change in the future, said Jackson, a geophysicist at the Swiss Federal Institute of Technology in Zurich, Switzerland.
This is where the dodo comes in.
Later extinction date?
In the course of looking at past geophysical measurements around the globe, Jackson ran across several writings by Benjamin Harry, a 17th-century British sailor and scientist who was the first person to measure the inclination, or angle, of the Earth's magnetic field in various spots in the Southern Hemisphere. This measurement helped to vindicate the idea that the planet had such a field emanating from deep underground, and helped give rise to the modern understanding of geomagnetism.