Sky – el cielo
(Pronounced thee-eh-loh)
To remember that sky is pronounced thee-eh-loh (cielo) in European Spanish, use the following mnemonic:
By shouting into the sky, her theory was that she could say "hello!" (cielo) to passing aircraft.

Cielo is masculine so it el cielo. Imagine a herd of elephants flying through the sky.

Examples of cielo (sky) in a sentence
El cielo está muy azul hoy.
(The sky is very blue today.)
Las estrellas brillan en el cielo por la noche.
(The stars shine in the sky at night.)
Los pájaros vuelan alto en el cielo.
(The birds fly high in the sky.)