My cyber son in Japan emailed me these questions:

I want to ask you a question about a usage of English. You say "heavens", "skies". Why are they plural ?

What is the difference from the singular "heaven", "sky" ?

Latin seems to have this usage of plural form, too, as I often see such examples in the dictionary's example sentences.

Can you help me with my answer to Junya?

I think that skies can be explained as morning or evening skies. They are the same but different you have the night skyearly morning sky. Just different looking skies. Plus his sky is different from ours. That's multiple vies... Heavens... Heavens on a religious thought do all Gods live in a single heaven? Heaven is the house of a God or gods. And Odin lives in a different Heaven than Jesus or Zeus. Different Heavens for different gods is my guess.

As buttler73 said: skies is used for "night sky", "cloudy sky" etc. so you have many different skies.

Heaven/Heavens on the other hand is not only used as a reference for Heaven in a religious manner...

It is often used literary in books and texts to describe the sky in a more poetic way.

Thanks you guys, I couldn't believe my eyes when I realised other people think about these things too. And what fantastic, enlightening answers.