What are the first recognizable forms of life that we find in the
geological record? How far back can we go in geological time and still
find life? This lecture reviews three lines of evidence that have
emerged in recent years to suggest that life may have emerged very early
on the young Earth, perhaps within a few hundred million years of the
end of the ... 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
<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
