lect 16 - Our Galaxy The Milky Way Chapter 23 Interstellar...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Our Galaxy: The Milky Way Chapter 23
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Interstellar dust obscures our view at visible wavelengths along lines of sight that lie in the plane of the galactic disk
Image of page 2
Interstellar dust makes difficult to locate the Sun within the galaxy The Sun Herschel’s map of our galaxy • William Herschel (18 th century) counted the number of stars at different regions of the sky, and concluded we were at the center • Jacobus Kapteyn (early 1900s) came to the same conclusion by analyzing the brightness and proper motions of a large number of stars • Because of interstellar extinction they actually observed only the nearest stars, and arrived at a wrong conclusion.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
This dilemma was resolved by observing parts of the Galaxy outside the disk
Image of page 4
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Globular clusters are a spherical distribution of roughly 10 6 stars packed in a small volume
Image of page 6