el cielo es (if you're describing something permanent about it)
el cielo esta (if it's something impermanent)
The color blue in Spanish is azul.
No, they are not blue, but people say that they where originally purple when they where first discovered
Translation: pengüinos morados
Translation: morado oscuro
Translation: calcetines morados
Translation: ardilla morada
Translation: bestia morada
"Purple Acres" is a proper noun, so it would be improper to translate.
Translation: marrón y púrpuro
La puerta es morado.
azul
I would say beige, pink or green.