1. Our galaxy is about 30 kpc in diameter. Our local group of galaxies is about 3 Mpc in diameter. Is the Cepheid Period-luminosity relation useful for measuring distances to the following objects: (A) Another star in the Milky Way? (B) A neighboring galaxy located within the local group? (C) A galaxy outside the local group? For each object, briefly explain your answer.
2. If you win-tea to determine the distance to a Centauri, which method (parallax or the Cepheid period-luminosity relation) would you use and why? Why couldn't you use the other? Hint: a Centauri is the closest star to the sun and is not variable.