Physics4kids
Physics 4 Kids: Where Traditional Physics Stops
We're about to move into the modern age of physics. In the early 1800's, scientists began examining the basis of matter, space, and time. Sometimes it gets very confusing, but the big idea is that Newton's physics describe about 90% of...
NASA
Nasa Star Child: What Is a Light Year and How Is It Used?
This is a definition and example of how distance is measured in astronomy, such as the distance between our earth and the stars.