NSF Astronomy and Astrophysics Fellow at the Harvard-Smithsonian Center for Astrophysics.
Writing in progress...
Starting with the northern hemisphere view of the night sky, discuss the life cycles of stars and touch on galaxies.
Q: Does this constellation look familiar to anyone?
Orion is a nice constellation to talk about astronomy. Betelgeuse is the "armpit" of the giant, and Rigel is the "foot."
Q: What color is Betelgeuse? [Red] What color is Rigel? [Blue]
Q: Think of a flame. Maybe a campfire, a gas stove, or a match. Which color is hotter? Blue or red?
[Blue is hotter]
Q:Which star do you think is hotter, Rigel, the bluer star, or Betelgeuse, the redder star?
[Rigel]
Do you see what we just did? We took the physics that we understand here on Earth, and applied it to outer space.
Betelgeuse is a pretty neat star. It is a red supergiant, and if it was were the Sun is, it's surface would go out passed Mars, almost to Jupiter's orbit. As huge as the star is, it's only about 10 times as massive as the Sun. In other words, its has a very diffuse atmosphere. If you flew into Betelgeuse, you wouldn't be able to say, "OK, we're on the surface!" You'd just notice it's getting very hot!