Kids can ask difficult questions, but it’s important to respond smartly instead of worrying about being technically correct
A kid asking questions is a good sign, as it reveals their curiosity and interest in understanding the world. As a parent, you need to respond in an encouraging manner even if you may not know the right answer. It is important to understand that kids are not looking for complex scientific answers. They just need a simple way to understand the world around them.

How should I explain to my 8 year old why the moon seems to follow us?
A curious child is bound to notice how things operate in this world. And they may have questions for things they do not properly understand. Many kids have queries about celestial bodies such as the sun, moon and stars. For example, your child may ask why the moon seems to follow us. This can seem difficult to answer, but there are multiple ways you can manage this situation.
Simple kid-friendly explanation
You first need to offer a simple explanation. You can say that the moon seems to follow us because it is very far from earth. You can offer an analogy of a moving car, where the roads and trees pass through quite quickly. In comparison, a distant mountain may appear to move much more slowly. Something similar happens with the moon, which is much further from earth.
As the car drives, it appears that the moon does not move at all. It gives the impression that the moon is moving with us. However, in reality, it is just an optical illusion due to the vast distance involved. You can also tell your kid that other celestial bodies like the sun and stars behave in the same manner due to the vast distances.
Fun ways to explain why the moon seems to follow us
If you want more interactive ways to answer your kid's queries, you can try out some fun experiments. For example, you can perform a finger test where you hold your finger close to your face and move your head side to side. When you do this, your finger seems to jump around a lot against the background. Now perform the same test with an object that is farther away, like a tree or a pole in a distance.
In this case, there won't be any major movement. The Moon is like that far-away thing, but much farther. Another experiment you can do is to draw a big circle representing earth. Next, place a tiny car on it. Put a piece of paper representing the moon far away from the paper that has the big circle drawing. When you move the car a little, the line of sight to the moon hardly changes angle.
Don't fuss over technical details
While you may want your child to have the right information, getting too much into the details may not be helpful. For example, trying to explain the distance from earth to moon (~384,400 km) and the rotations and revolutions may confuse your child even more. Similarly, there are various concepts involved here such as parallax, relative motion, etc. It is apparent that you need to focus on providing a simple answer instead of getting into complex scientific details that your 8-year old kid is unlikely to grasp properly.