Talk Archives

From the early Mercury missions (1961) until now, astronauts have been observing and photographing the Earth. Dr. Willam Muehlberger shares the many Earth's surfaces that were first identified by astronaut observations and how insight into geological, atmospheric and oceanic processes can be discerned through these images.

In the 1970s, the theory of plate tectonics suggested that a great episode of volcanic activity led to a severe environmental decline and catastrophic die-off of the dinosaurs and many other species. More recently, a spectacular new hypothesis claims that an asteroid impact wiped out the dinosaurs in one of the most cataclysmic extinctions in Earth history. Dr. Timothy Rowe looks at new evidence and possible causes for dinosaur extinction.