Share Lecture 30: Goldilocks and the Three Planets

Copy link

November 05, 2009

Lecture 30: Goldilocks and the Three Planets

46 minutes

Why is the Earth habitable today but Venus and Mars not? This lecture

explores the question of planetary habitability from the perspective of

the stability of liquid water on the surface of planetary bodies. We

will see how the amount of sunlight and the greenhouse effect in the

atmosphere combine to create a classic Goldilocks problem: whether or

not a planetary surface has stable liquid water is a question of not

being too hot or too cold. This defines the Habitable Zone for the

present-day Sun. However, the size of a planet also plays a role, and

we will expand the concept of habitability to include the type of

atmosphere a planetary body can or cannot retain. Finally, because the

Sun changes brightness slowly over its lifetime, the location of the

habitable zone is time-dependent. We will define the Continuous

Habitable Zone, and discuss implications, and limitations, of the idea

of habitable zones, looking forward expanding our search for life to

worlds around other stars. Recorded live on 2009 Nov 5 in Room 1005

Smith Laboratory on the Columbus campus of The Ohio State University.

...more

By Richard Pogge