Mainly for the color. Here's a decent reference I use sometimes when I'm lost for hues :-D The piscine symbolism is also somewhat apt because the sky can be conceived of as a vast ocean.
Antares is among the brightest stars visible from Earth (on average the 15th brightest). It is a red supergiant approximately 550 light years away. The color likely inspired the artist to create the piece I used as the thumbnail image.
Because it is part of the Scorpius constellation, one of its nicknames is "the heart of the scorpion" which I referred to in the opening line of the poem. I also drew inspiration from the odd trees in the image which somewhat resemble rose rocks. (My grandma lived in Oklahoma, where rose rocks, though rare, are often found. I thought they were amazing as a child!)
Omg that link is awesome! And yeah, I know about Antares! Now that you said all of this, it makes the poem more awesome... It's hard to read your mind but that's good. It means it's not shallow ;)
Have a great night bro