The causes the tail of a comet always to trail away from the Sun. In general, an asteroid doesn't have an atmosphere, but some asteroids are large enough to have their own . Most meteoroids that enter Earth's atmosphere vaporize before they ever reach the surface creating trails of light as they burn, known as or shooting stars. Space travel along curved trajectories and take advantage of the gravity of other planets in the process. The probes explored Mars, Venus, and Mercury, and they were responsible for the first close-up images of these planets. Respond to the following based on your reading. Give examples of the scientific knowledge that has been gained by space exploration.