1. The first question asks about the size of certain solid bodies in space, specifically their diameter in kilometers. 2. These solid bodies are typically asteroids or planetesimals, which are often hundreds of kilometers in diameter. 3. The problem is to identify the size of these bodies, which is given as "kilometers in diameter". 4. The key formula or concept here is understanding that these bodies are large enough to be measured in kilometers, often ranging from tens to hundreds of kilometers. 5. For example, many asteroids in the asteroid belt have diameters ranging from a few kilometers to several hundred kilometers. 6. Therefore, the answer to the question is that these solid bodies are "hundreds of kilometers in diameter". This completes the solution to the first question.