Why is this the answer?

The answer is shadow because this super clever riddle is talking about how the sun makes your shadow look different throughout the day. A shadow is a dark shape you make on the ground or a wall whenever you stand in the sunlight. It is the spot where your body is blocking the light from getting through. To solve this fun riddle, you just have to think about where the sun is in the sky at different times. First, the riddle says the answer is "Tall in the morning." In the morning, the sun is just starting its journey and is very low, close to the horizon. That low angle is why the light hits you from the side, and this stretches your shadow out long and skinny. It looks tall, like a huge giant standing beside you! As the day goes on, the sun slowly climbs higher and higher into the sky. When it reaches the highest point in the middle of the day, which is "noon," the sun is shining from directly above your head. This changes the shadow completely, and it becomes "short at noon." When the light is shining straight down, your shadow shrinks until it is a tiny, compact shape right below your feet. Sometimes, it is so small you can barely see it at all. Finally, the sun sets, and it gets dark. That is when your shadow is "gone at night." Without a big, strong light source like the sun, you cannot see your natural shadow outside anymore. It disappears because there is no light for your body to block and turn into a dark shape. But the last line gives the final, reassuring clue: "But I'll be back soon." This is the perfect ending because you know that the sun always rises the next day, and as soon as the light returns, your shadow will be right there with you again. This riddle is a wonderful and smart way to remind us how the sun’s movement across the sky affects what we see on the ground every single day.