At some point on the journey back to Erid, Rocky gets around to asking Grace exactly why he was so mesmerised by seeing the astrophage in the Petrova line.
Grace describes it as best he can, but all he can really manage to get across to Rocky is that he was surrounded by small floating lights.
Later on, Grace is talking about the stars and how important they've been to human cultures for millennia. “What do the stars look like, question?” Rocky wants to know.
Oh, y'know, they're a bunch of small floating lights.
There's a disco ball on the Hail Mary. Grace says it's there because it “makes me happy”. “How does it make Grace happy, question?” Rocky wants to know.
Oh, it creates the illusion that he's surrounded by small floating lights.
Rocky begins to do some research.
Glitter: a substance invented by humans to make things look like they're covered in small lights.
Human jewellery: mostly involves gemstones or polished metals, designed to reflect small lights.
Christmas lights. Candles. Lanterns. Fireworks. Glowsticks. Glow in the dark paint. Rocky is beginning to notice a pattern here, statement.
It takes Grace a fucking while after getting to Erid to notice that a lot of the gifts he's receiving from grateful Eridians are either a) sparkly, b) incredibly shiny, or c) fitted with lights.
While the last one is obviously a concession for his human light sense, he's confused about the former two. Are Eridian materials usually this shiny? Is there some quality about sparkly or highly polished surfaces that makes them sound better? Or is there something about Eridian geology/metallurgy that makes their materials like this?
He asks Rocky about it.
“Simple. I tell people humans like lots of small lights. Humans are easy to make happy.”
Grace kind of wants to protest that humans are much more complicated than that.
But honestly… it fucking works. Like yeah the polished gemstones, shiny metals and glittery rocks are beautiful. Yes those Christmas lights you put up around the house did markedly improve my mental health, Rocky. Thank you, I hate it.
Grace spends a lot of time trying not to think about whether his species' urge to explore the cosmos (that saved their planet and nearly killed him several times) is tied to the same instinct that made his students like glitter gel pens.
