Q21: How did Leavitt know that the Cepheid variables she was studying were all at about the same distance from the earth?

Q21: How did Leavitt know that the Cepheid variables she was studying were all at about the same distance from the earth?

A. Because they were all on the same photographic plate

B. A. Because they were all in the southern hemisphere

C. Because they all had the same apparent brightness

D. Because they all belonged to the same Magellenic Cloud?

Q8: Suppose you look at Venus through a Galilean telescope when it first appears as the morning star. Which of the following are true?

A. it looks round and fully lit

B. it appears crescent with the east side lit up

C. it appears crescent with the west side lit up

D. it appears on the western part of the horizon

Q4: Which of the following is false?

A. A refracting telescope can have two convex lenses

B. A refracting telescope can have one convex and one concave lens

C. A reflecting telescope has no lenses at all

D. A reflecting telescope has a parabolic shaped mirror