Which of the following best describes the Milky Way Galaxy?
A) a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars
B) a spherically shaped collection of stars including our solar system and about a dozen other solar systems, stretching about 4 light-years in diameter
C) a spherically shaped collection of about 1 million stars that is about 100 light-years in diameter
D) a spiral galaxy with a disk about a billion kilometers in diameter and containing between 100 million and 1 billion stars
E) a spiral galaxy with a disk about 100,000 light-years in diameter and containing about 100,000 stars
Question 2
The core, mantle, and crust of a planet are defined by differences in their
A) temperature. B) density. C) strength. D) geological activity.
