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
Umbra
The central part of a shadow where the light source is completely obscured. During a total lunar eclipse the Moon lies within Earth’s umbra. The surrounding penumbra receives light from part of the source and produces a less complete darkening.
What to look for
NASA's airborne view of the 21 August 2017 total solar eclipse. The Moon blocks the bright photosphere, revealing the corona.
