That's two books I've read by this author now, and I've given both of them three stars. I was more impressed by this one than the other (Maphead), but there are some flaws here that can't be ignored (and, judging by the other reviews here, others feel the same).
The idea for the story is good. The author writes inventively and her descriptions of things are nice. The ending is okay.
The style of writing is such that it makes the book difficult to read. I know what the author is trying to do because I've probably done the same course as she has, but it doesn't quite come off. My writing sufferers from the same problem: it's challenging to keep track of who is saying what, which leads to me having to skip back to check. I (and this author) probably just need to make more use of 'he said', 'she said', which is onerous but makes the text more readable.
On top of that, the story is just a bit too woolly and confusing. I mean, I read it through in a couple of days, but I had to force myself.
And another thing: the author really needs to work on her blurb writing skills. The one for this book does not really match what the story is about. It's really a missed opportunity to promote the book. I buy on the basis of what I read on the back (which kinda makes me wonder, now, why I bought this book).
Anyway, read it if you're obsessed with how the world will be if the sun heats up and blots out a lot of life. Avoid it if you're pedantic (like me).