Here's why:
* Unequal Masses: The Earth is significantly more massive than the Moon. The Earth's mass is about 81 times greater than the Moon's mass.
* Center of Mass Calculation: The center of mass is calculated based on the masses and relative distances of the objects in a system. Because the Earth is so much more massive, the center of mass is closer to the Earth's center than the Moon's center.
* Orbital Motion: Both the Earth and Moon orbit around this common center of mass. Although the Earth is much larger, it actually "wobbles" slightly as the Moon pulls on it. This wobble is what we detect as the Earth's tides.
Think of it like a seesaw: If you have two people on a seesaw, the heavier person needs to sit closer to the fulcrum (the center of mass) to balance it. The same principle applies to the Earth-Moon system.
