The Cosmic Distance Ladder

1
The Cosmic Distance Ladder
Dr. Frederic V. Hessman Universitäts-Sternwarte
Göttingen
2
II The Distances to the Stars
External Galaxies
Our Galaxy
Geometrical Parallax (Tuesday)
Solar System
3
Early Ideas
Aristarchus (310-230 B.C.E.) Sun at center of
solar system Archimedes Must see parallax of
stars
4
The Fixed Stars
Edmund Halley (1656-1742) Noticed that
Hipparchos stars moved ½ degree in 1800 years
Proper Motions
5
Astrometry
6
Stellar Parallaxes
Parallax
Friedrich Bessel (1838)
7
Stellar Proper Motions
1967
1950
Barnards Star
8
A Proper-Motion/Parallax Simulator
http//www.astro.washington.edu/labs/parallax/java
_parallax.html