Two Years that Changed the Milky Way Galaxy: 1951 and 2018

press release:

Lecture by Dr. Bob Benjamin, UW-Madison Physics Dept.

Starting with the first star-count maps of the sky by William and Caroline Herschel in 1785, our astronomical understanding of the structure of the Milky Way Galaxy has been a gradually unfolding process. But there have been two extra-ordinary years in which our understanding of the Galaxy has changed at a break-neck speed. The first was 1951 when the first evidence for the spiral nature of our Milky Way was discovered here in southern Wisconsin at Yerkes Observatory in Williams Bay, Wisconsin. The second year is 2018 when the measurements of the distances and sky motions of a billion stars by Gaia—a European Space Agency mission—has astronomers scrambling to remap the Galaxy and see how well the previous view of our Galaxy holds up. Big changes are afoot, and Dr. Benjamin will describe what has been discovered in the past few months.