Here's why:

* Gravity's Pull: Every object with mass exerts a gravitational pull on every other object with mass. The larger the mass, the stronger the pull.

* Balance of Forces: For an object to be in orbit, the force of gravity pulling it towards the larger object (like a planet) must be balanced by the object's inertia (its tendency to move in a straight line).

* Circular Motion: This balance results in the orbiting object constantly falling towards the larger object, but also moving fast enough sideways to miss it, creating a curved path – an orbit.

Think of it like swinging a ball on a string. The string represents the force of gravity pulling the ball towards your hand (the larger object). The ball's inertia, its tendency to keep moving forward, causes it to swing in a circle.

Let me know if you'd like more details about orbital mechanics!