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.
Other
Online Conversion
Conversion calculators galore! Convert just about anything from one measureable unit into another measureable unit here with over two dozen calculators. Each of the links is specific to a measureable quantity. Some examples include...
Other
Ask Numbers: Measurement Conversion Calculators and Charts
What kind of unit conversion would you like to do? This site will allow you to do a multitude of conversions. Just click on the specific measurement you are needing to convert. It also provides a history of measurements and a chart of...