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 pl ... Show More
Nov 2009
Lecture 31: The Properties of Stars
What are the observed properties of stars? This lecture is a quick review of the basic observational properties of stars, introducing luminosity, spectral classification, the luminosity-radius-temperature relation, and the Hertzsprung-Russell (H-R) diagram. This sets up the empir ... Show More
46m 37s
<p>La durée de vie d'une étoile peut nous renseigner sur sa composition et sur l'existence éventuelle de la vie dans le cosmos. mais, en dehors du Soleil, il est assez difficile de déterminer l'âge d'une étoile.</p><br><p>L'importance de la masse</p><br><p>En évaluant, grâce à la ... Show More
