AstronomyCast 254: Reflection & Refraction

We finally get organized enough deal with several listener questions: isn�t dark matter just regular stuff we can�t see? how can parts of the Universe be expanding faster than the speed of light? what will Betelgeuse look like when it explodes as a supernova? what�s the speed of gravity? All these and more questions are answered.

18 Joulu 200629min