Question : 157) Why do blue stragglers show up in globular clusters? 158) : 1828929

157) Why do blue stragglers show up in globular clusters?

158) High-precision observations by the Hubble Space Telescope have revealed what as-yet unexplained phenomenon in globular clusters?

159) How has the chemical composition of the Sun changed in the last 4.5 billion years? How will this affect its future?

160) Why are there no black dwarfs yet, but in the future they may make up the majority of normal matter in the universe?

161) Under what conditions will a nova occur?