1. Pop-quiz #22 Which of the following statements is FALSE?
When a star finishes burning all the hydrogen in its core, it ceases to be a main sequence star
The “helium flash” (ignition of the helium core) takes place at the tip of the red giant branch
A planetary nebula is formed when a star loses part of its outer envelope in a stellar wind and this is the material from which planets are formed
The Zero Age Main Sequence represents the locus of points on the HR diagram where nuclear fusion starts

2. Pop-quiz #23 Which of the following statements is TRUE?
The constancy of the speed of light is a basic principle of the Special Theory of Relativity
The General Theory of Relativity was designed to explain situations where the speeds of objects are close to the speed of light
The Special Theory of Relativity states that a moving ruler is measured to be longer than its twin ruler at rest
The mass or inertia of an object decreases when its speed approaches the speed of light

3. Pop-quiz #24
Which of the following statements is FALSE?
Stars in the disk of a spiral galaxy tend to be younger than those in the bulge
Observations of globular clusters in the Milky Way led Shapley to conclude that the Sun is not located at our Galaxy’s center
Most galaxies are thought to have massive black holes at their centers
Stars in an elliptical galaxy move in a coherent fashion about the galaxy’s center