Dear Iris, Scientists figured out that the other giant planet used to be there because of the effect it had on everything around it. The other planets and their moons would have different orbits if there hadn’t been something else that size pulling on them. Our whole solar system would be different. We wouldn’t have seen Jupiter that day you were at my house because it would be in another part of the sky. Even though that planet has been gone a long time and it’s really far away now, it still affects the planets it used to share space with. Come back soon, Iris. It’s not the same here without
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