Because of an obscuring atmosphere,an observer in a distant galaxy can only see the nearest 1,000 stars to his or her home planet.How could the observer most directly determine that he or she lives inside an elliptical galaxy?
A) by measuring the brightnesses of the stars
B) by mapping the locations of the stars on the sky
C) by measuring the differences in velocities between the stars
D) by measuring the masses of the stars

Question

Quizplus · Accepted Answer

Measuring the differences in velocities between the stars could allow the observer to determine whether they live in an elliptical galaxy. In elliptical galaxies, stars tend to have more random orbits and velocities compared to spiral galaxies, where stars often have more ordered circular orbits. By measuring the differences in velocities between the stars, the observer could look for any patterns or trends that suggest the galaxy has an elliptical shape.

Because of an Obscuring Atmosphere,an Observer in a Distant Galaxy