Now that youth has taken travel to the moon in his intellectual stride, he contemplates new frontiers. In this easily worded text, travel to the planets beyond Mars is considered, exploration which may result in discovering planets similar to ours on which natives of the World can colonize. What is the probability of there being such planets, how shall we reach them, what will such trips involve, how do we arrive at these calculations? These and other questions which will intrigue even the most indifferent science students are posed and reasonably answered. A recommended supplement for school study, this should do much to boost the young reader's interest in astronomy.