ASTR 103 Lecture Notes - Lecture 18: Henrietta Swan Leavitt, Cosmic Dust, Magellanic Clouds
Document Summary
Interstellar dust obscures our view at visible wavelengths along lines of sight that lie in the plane of galactic disk. William herschel maps out the distribution of stars and gets: the universe of herschel. William parsons, 3rd earl of rosse, builds the leviathan of parsonstown - draws a. Henrietta leavitt and the cepheid p-l relationship. Period vs. magnitude of cepheids in smc. H. shapley maps distribution of globular star clusters using cepheids . Where is the mass centered? we are not at the center. At visible wavelengths, the center of our galaxy suffers ~30 mag of extinction by dust. Even with big modern telescopes, we cannot see very far in the plane of our galaxy at visible wavelengths. Debate solved nothing- questions in science are not solved by debates, but by observations and experiments. Nature of the spiral nebulae and the great debate . 1923- hubble measures distance to m31 using cepheid variables- ending the debate.
