Find a term from the labs, understand the process behind it, and see how it appears in the landscape. Each entry connects an explanation with a real observation and a model you can explore.
Term
Terminator
The boundary between the illuminated and dark hemispheres of a planet or moon. Earth's rotation carries places across it; changing solar declination alters its seasonal orientation.
What to look for
Meteosat-9 SEVIRI, 20 March 2011. The terminator passes close to both poles around the equinox; refraction and the Sun's finite disc mean observed daylight is not exactly twelve hours everywhere.
