text: We found 50 resources with the concept astronomers
  Dark matter accounts for 23 percent of the known universe, yet scientists don't know what it is. No one can see it, but everyone knows it is there based on the weight of the universe. Even though it isn't invisible, it does have an...
  In this characteristics of stars instructional activity, students answer short answer questions as they relate to characteristics of stars, star groups, H-R diagram, and galaxies.