Cielo vs. firmamento
The Spanish words 'cielo' and 'firmamento' both translate to 'sky' in English, but they are used slightly differently based on context.
Cielo
'Cielo' is the most common word for 'sky' and is used in both everyday and poetic language. It can also refer to 'heaven' or a spiritual realm in religious contexts.
Las estrellas brillan en el cielo.
(The stars shine in the sky.)
El cielo está despejado hoy.
(The sky is clear today.)
Mi abuela cree que su perro está en el cielo.
(My grandmother believes her dog is in heaven.)
Firmamento
'Firmamento' is a more formal or literary term for 'sky'. It can also convey a sense of grandeur or celestial beauty, often used in poetry or scientific contexts.
Los astrónomos estudian el firmamento cada noche.
(Astronomers study the sky every night.)
El firmamento está lleno de misterios por descubrir.
(The firmament is full of mysteries to uncover.)
Las figuras mitológicas se dibujan en el firmamento estrellado.
(Mythological figures are drawn in the starry firmament.)
Summary
The word 'cielo' is commonly used in daily conversation to refer to the sky or heaven. In contrast, 'firmamento' is more formal, often used in poetic, scientific, or literary language to describe the overarching sky with a sense of grandeur.