Blue flies into the sky, so the sky is blue.

蓝色飞入天宇，所以天空是蓝的。

youdao

There is blue sea and blue sky.

这里有蓝色的大海和湛蓝的天空。

youdao

Sky is blue, and water is also very blue.

天很蓝，水也很蓝。

youdao

This was because all you could see was the very blue sky and the very hot sun.

VOA: special.2009.01.14

Maybe it could refer to either the poet or the sun throughout the entire line, if you think of the mantle blue as being the actual sky that the sun is able to twitch over his shoulder.

或者两者皆可,从整句的行文看来，如果你们把蓝色的丝巾看作是真实的天空的话,那么太阳的确是能够在他的肩上轻轻颤动。

耶鲁公开课 - 弥尔顿课程节选

I think it was because people were overselling investments and saying, there's no limit to this investment but the blue sky above.

我想这是因为,当时人们过度宣传投资产品,并宣称,投资收益无止境,如头顶的蓝天那么遥远

耶鲁公开课 - 金融市场课程节选

Clearly intended as a consumer product, the EM-500 is available in five colors: yellow, blue, green, red and sky blue.

CNN: Review: Design makes the difference for pocket-PC gadgets

This refraction eliminates both the red end of the spectrum (red light is not bent enough by the air layer to form part of the second image) and the blue frequencies (which are scattered away: this selective scattering is why the sky is blue).

ECONOMIST: In a flash

We all know that if I said the sky was blue you would argue that the sky was red and throw in some insults for extra measure.

FORBES: Newt Gingrich --Tax Cheat?