The most abundant molecule in molecular clouds is

Study this H-R diagram. Which of the following stars is the most massive? (The red arrows help you locate these stars on the diagram.)

Study this H-R diagram. What is the spectral type of the star Sirius? (The red arrow helps you locate Sirius on the diagram.)

Why do we think the first generation of stars would be different from stars born today?

Briefly describe two key pieces of evidence that support the Big bang Theory.

This is the H-R diagram for stars in a 12-billion-year-old globular cluster. Based on our understanding of stellar lives, which of the four labeled stars is currently generating energy through hydrogen fusion in a shell around an inert (nonburning) helium core?

Why do orbits of bulge stars bob up and down?

This diagram represents an edge-on view of our Milky Way Galaxy. Of the four labeled stars, which one is located in what we call the halo of the galaxy?

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

A spacecraft is on a trajectory that happens to be taking it near a black hole. Which diagram shows how the spacecraft’s orbit will be affected?