There are certain incredible things about childhood that we tend to lose with age. Wonder is one of them. Children have an innate ability to simply... wonder.
What happens to us? As we age (and learn) we may simply have less to wonder about. As we get accustomed to reality, we may find that wondering disappoints more often than it gratifies. In fact, practically everything we do in life we do for the results. Work, exercise, study are all finitely results-oriented. Even many recreational pastimes depend on the score or the win. We often forget that the purpose of wondering has nothing to do with the result.
It's true, curiosity prompts us to pursue specific goals—finding answers, understanding concepts or solving problems. Curiosity is educational. It stems from strategy, or the active desire to complete a void. It can thus be satisfied, tied up neatly with a bow and effectively discarded.
Wonder, on the other hand, happens abstractly. Imaginatively. It generally lacks boundaries, structure, direction or finish lines. Its extreme passivity demands little to no investigation whatsoever. Our wonders lead us from one idea to another without making us feel the need to define, answer or complete the nebulous progression of thought. Wonder is not so suicidal as curiosity. It doesn't need to find the answer.
Perhaps that's why no cats were ever killed by wonder.