Whew. Finally back after two snow days and then a 3 day weekend and a 2 hour delay today! We are on to the HR diagram today and a quick discussion of relative abundance of stars. The above diagram is one of my favorites. Always interesting to talk about how big a million cubic parsecs would be. The question of the week on xkcd is about stars and grains of sand but with a twist worth thinking about! Click on image below.
Today we got out the celestial spheres and started our discussion of celestial coordinates. Students learned how to describe the position of a star using right ascension and declination. Always impressed with how interested they are and how quickly they catch on. We set the spheres to today’s date and discussed the autumnal equinox this weekend and the sun’s position when it rises, is at solar noon, and when it sets.
Students in astronomy are using this interactive site from the U of Nebraska-Lincoln to better understand the HR diagram. The site is on the class Moodle so they can came back to it easily. There are a number of good astronomy apps at this web site.