Scientists are beginning to develop the technology to observe other Sun-like stars distant from our solar system. They can even detect large Jupiter-like planets orbiting some of these stars. Other stars appear to have no planets, but astronomers can see the star wobble a bit in space. What do you think this means?

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.