Lecture 25: A Tale of Two Galaxies, The Milky...

What are Spiral Galaxies? This lecture describes the basic properties of spiral galaxies, their patterns of rotation and how that lets us measure their masses, and the nature of the spiral arms as waves moving through the disk and triggering formation of new stars. Recorded 2006 ...  Show more

What are the different types of galaxies? What hints can they give us as to the structure and evolution of galaxies? This lecture introduces the Hubble Classification System for galaxies, and describes the properties of each major class. This detailed overview gives us some tanta ...  Show more

A new podcast, Astronomy 141, Life in the Universe, is available for those interested in continuing an exploration of topics in modern astronomy. 

What is Astronomy? What is Science? What is the course all about? Brief introductory remarks after going over course mechanics on the first day of Astronomy 161 for Autumn Quarter 2007. Recorded 2007 Sep 19 in 1000 McPherson Lab on the Columbus campus of The Ohio State University ...  Show more

Are we alone in the Universe? This lecture explores the question of how we might go about finding life on planets around other stars. Rather than talking about speculative ideas, like the Drake Equation or SETI, I am instead taking the approach of posing it as a problem of what t ...  Show more

Get ready to explore a 10 billion year old mystery! A closely bound duo of energetic quasars, the hallmark of a pair of merging galaxies, have been discovered when the Universe was only 3 billion years old. What secrets do these quasars hold and why have they lasted so long? Join ...  Show more