How do we determine the Milky Way’s mass outside the Sun’s orbit? 

Why would one expect lower velocities of stars as they orbit further from galactic centre? 

Which type of galaxy is lenticular? 

Which statement accurately describes how observations of distant galaxies help us learn about galaxy evolution? 

What does the expansion of the Universe imply about its beginning? 

Starburst galaxies are especially bright in 

What is the name of the cluster of galaxies our Milky Way galaxy resides in? 

Which of these statements is a key assumption in our most successful models for galaxy formation? 

Why do virtually all the galaxies in the Universe appear to be moving away from our own? 

Which

of the following claims about the very first stars in the universe

would be impossible given our basic picture of the history of the

universe?