Final answer:
Population I stars are younger and found in the galaxy's disk with circular orbits and are rich in heavy elements, while Population II stars are older, located throughout the galaxy with elliptical orbits and are poor in heavy elements.
Step-by-step explanation:
The main answer to the difference between Population I and Population II stars lies in their ages, locations, and chemical compositions. Population I stars can have a wide range of ages, from those still forming today to others that are as old as 10 billion years. An example of a Population I star would be the Sun, which is about 5 billion years old. These stars are typically found in the disk of the galaxy, have nearly circular orbits around the galactic center, and reside in areas rich in interstellar matter and molecular clouds like the spiral arms and open star clusters.On the other hand, Population II stars are uniformly old, with typical ages ranging from 11 to 13 billion years. They formed early in the history of the galaxy when the abundance of elements heavier than hydrogen and helium (heavy elements) was low. Population II stars tend to have elliptical orbits that can take them far above the galactic disk into the halo, and they show no correlation with the spiral arms. Globular clusters in the Galaxy's halo are mainly comprised of Population II stars.As for the explanation in more than 100 words, it's necessary to understand that stars are born from clouds of dust and gas in the galaxy. The chemical composition of these clouds evolves with each generation of stars, as elements heavier than hydrogen and helium are produced in the cores of stars and spread into the interstellar medium when stars die. Consequently, Population II stars, which formed earlier, are poorer in heavy elements compared to Population I stars, which formed later or are still forming, enriched by materials from previous star generations.Conclusion The key distinction between Population I and Population II stars is their age, location within the Galaxy, chemical composition, and orbit, which reflects the evolutionary history and ongoing processes of star formation in our galaxy. Understanding these differences not only informs us about the stars themselves but also about the history and structure of our galaxy.