1. Traveling in your starship, you observe a distant galaxy that is 870 million light years away and is moving away from you at a speed of 20,000 km/sec. How fast would you have to travel in order to be able one day to catch up to a galaxy twice as far away?
   at least 5,000 km/sec.
   at least 10,000 km/sec.
   at least 20,000 km/sec.
   at least 40,000 km/sec.
   at least 100,000 km/sec.

(You have to be moving at least as fast as the distant galaxy in order to be able to catch up to it!)

2. You observe three distant galaxies and note their apparent radial velocities:
   
   • BFG-01 39,300 km/s
   • BFG-02 79,000 km/s
   • BFG-03 19,000 km/s
   Which of the following is true about these galaxies?
   BFG-02 is twice as big as BFG-01.
   BFG-03 is the most massive galaxy.
   BFG-02 is the least massive galaxy.
   All of the Above.
   None of the Above.
   

   (A galaxy's radial velocity depends on its distance, not on its size)

	Click here to learn about the Doppler shift and how Hubble knew these galaxies were moving away from us.
	Click here to find out what Hubble's findings tell us about the Universe!
	Click here to go to get the data to solve this problem using Hubble's Law.
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