Cells are the basic structural and functional unit of all life on Earth.
This lecture reviews the basic building blocks of cells, the main
chemical components, the two basic types of cells (Prokaryotes and
Eukaryotes), and introduces the Phylogenetic Tree of Life, the way
biologists order life by their biochemical and genetic relationships.
Understanding li ... 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
