Why is this the answer?

The answer is moon because this is a fun and clever riddle that describes our glowing neighbor in the night sky. Let us look at the clues one by one to see how they point to the moon. The first part of the riddle says, "I'm white, I'm round." When you look up at night and see a big, full circle, that is the full moon. It looks perfectly round like a giant white ball hanging in the darkness. The light you see is not the moon's own light. Instead, it is the sunlight reflecting off the moon's rocky, dusty surface, which makes it look bright white to us here on Earth. The moon is actually a silent, airless world that is much smaller than the Earth. Now, for the tricky part: "but not always around." The moon is always in space, traveling in a circle around the Earth. However, we do not always see the entire circle. As the moon goes on its path, the sun shines on different parts of it, which creates the moon's phases. Sometimes we see the whole circle. Other times, we only see a small, curved shape called a crescent moon. And sometimes, during what is called the "New Moon" phase, the part of the moon that faces us is not lit up by the sun at all. It is still there, but because it is completely dark on our side, we cannot see it, making it seem like it is not around. Finally, the riddle says, "Sometimes you see me, sometimes you don't." Even when the moon is in a phase that is easy to spot, other things can hide it. Big, dark clouds can float across the sky and cover it up completely, blocking our view. Also, the moon is often in the sky during the day, but the sun is so bright that its pale white light is hard to notice against the blue sky. The moon is our beautiful, mysterious space partner that likes to play hide and seek, but it will always come back to visit us on schedule.