So, Where is Everybody? Interstellar colonization, in principle, is an
exponential growth process that would fill the galaxy in a few million
years even with a very modest star flight capability. This is a small
fraction of the lifetime of the Milky Way Galaxy, so the Galaxy should
be teaming with life. But, we so far have no compelling evidence of
extra ... Show More
Sep 2009
Lecture 2: Astronomical Numbers
An introduction and review of the basic notation and physical units we will be
using throughout this course. In particular, we will be using the
Metric (SI) system for lengths, masses, times, and temperatures, and
special astronomical units for distances (AU and Light Years) and ... Show More
43m 56s
Mar 2022
Comment calculer l'âge d'une étoile ?
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.
L'importance de la masse
En évaluant, grâce à la radioactivité, l'âge d ... Show More
1m 58s