NASA
Nasa: Imagine the Universe: Welcome to the World of X Ray Astronomy
Site recounts how X-rays were discovered as well as who discovered them. Offers graphics, links to facts on this topic, a quiz, and teacher resources.
PBS
Pbs Learning Media: Birth of a Supernova, Type Ia
In this interactive activity from NOVA Online, learn about a type of exploding star - a Type Ia supernova - that is so bright that astronomers can measure the distance to the galaxy in which it resides, and even learn which elements make...