1. To determine the period of a pulsar accurately, astronomers must take Earth’s orbital motion around the Sun into account. Explain why. 2. The distance to the Crab Nebula is about 2000 pc. When did...

1. To determine the period of a pulsar accurately, astronomers must take Earth’s orbital motion around the Sun into account. Explain why.

2. The distance to the Crab Nebula is about 2000 pc. When did it actually explode?

3. To test your overall understanding of stellar evolution, do Interactive Exercise 13-5. You can print out your results, if required.