Meaning: This sentence tells us that there are many things about planets that we don't know or understand.
Choice of Words: "Secrets" are things that are not known or revealed. "Mysteries" are things that are difficult to understand or explain.
Alternative Expressions
Planets have many secrets and mysteries.
Meaning: This means that there are many things about planets that we still don't know about. It's like saying, We still have a lot to learn about planets.
Choice of Words:Planets are big balls of gas and rock that orbit stars. Secrets are things that are not known or told to many people. Mysteries are things that are hard to understand or explain. When you put them together, "Planets have many secrets and mysteries" means that there are many things about planets that we don't know or understand.
Planets keep many secrets and mysteries hidden.
Meaning: This means that there are many things about planets that we still don't know about, and that these things are hard to find out. It's like saying, It's hard to learn about all the secrets and mysteries of planets.
Choice of Words:Planets are big balls of gas and rock that orbit stars. Secrets are things that are not known or told to many people. Mysteries are things that are hard to understand or explain. Hidden means that something is not visible or easy to find. When you put them together, "Planets keep many secrets and mysteries hidden" means that there are many things about planets that we don't know or understand, and that these things are not easy to find out.