Terrella and the Northern Lights

April 05, 2019


April 2019 Viewer's ChoicePhotographer: Robert Shafer 
Summary Author: Robert Shafer 

The odd looking device shown above is called a terrella. It's a metal sphere with a magnetic field that's hung in a vacuum chamber. When an electrical charge is set up between the sphere and one of the chamber's corners, electrical particles stream in towards the sphere, much like solar winds stream toward the Earth. Rings of light appear around the magnetic poles, similar to Earth's auroras. Early researchers, such as Kristian Olaf Bernhard Birkeland, used an apparatus such as this to help understand the cause of the northern lights (aurora borealis). Photographed at the Tromsø University Museum, Tromsø, Norway.

Photo Details: Canon EOS 7D MkII camera; Canon EF-S 10-22 mm lens; f/3.5-4.5 USM; 1/50 second exposure; f/4.0; ISO 8K.