RASC Regular Meeting
Sep 9, 2013
The days are getting longer!

 

20130909_dumberry Guest Speaker:
Mathieu Dumberry
University of Alberta

The days are getting longer!
— studying Earth’s rotation with ancient eclipse observations

Observations of Solar and Lunar eclipses over the past 2500 years reveal that the speed of rotation of Earth is gradually slowing down (an effect produced by tidal interaction with the Moon). The days are then getting longer, though only by a small amount, at a current rate of about 2 milliseconds per century. Small oscillations about that trend can also be observed. Oscillations on a similar timescale are also observed in the magnetic field recorded in rocks and archaeological artifacts. By combining them, we can learn about flow patterns deep inside the Earth’s fluid core. In this talk, Dumberry discussed how information on Earth’s rotation and magnetic field are obtained. Further, he discussed how their observed temporal changes provide opportunities to understand global planetary processes such as post glacial rebound and aspects of the dynamics in the Earth’s core that cannot be directly observed.