Whoah, hold the "AI" hype train there: I didn't design it that way, but an LLM is close to the worst possible thing you could use for this.
1. LLMs are incapable of real math or symbolic logic, so they aren't able to you whether your statement is approximately-true, and they can't tell you if it's useful either. (Lots of planets are spherical.)
2. You're trying to communicate with literal aliens that won't have any of that English training data the LLM draws from. They don't have any preconceptions about a "second" and "year" being related but one is bigger, they won't see the same colors or even have a 1:1 color sense, and they absolutely won't be inferring that Jupiter and Saturn are connected by pantheon-naming.
A lifetime exile from your entire species and culture is not something you want to leave to an LLM.