- Why is it difficult to measure the speed of light from points on Earth's surface?
- Explain how observations of Jupiter's moon, Io, provided evidence that could be used to calculate the speed of light.
- How does knowledge of the speed of light help astronomers determine the age of a far-off heavenly body?
- Measuring the speed of light is one example of scientists having to describe something that is "extreme," or, in this case, something really, really fast. Can you think of other examples where "extremes" are measured or described?
