What Happens Next by Claire Swinarski

Astronomy-obsessed Abby McCourt should be thrilled about the solar eclipse her small town of Moose Junction is about to witness, but she’s not. After her older sister Blair was sent away for an eating disorder, Abby has been in a funk.

Desperate to dull the pain her sister’s absence has left, she teams up with a visiting astronomer to help track down his long-lost telescope. Though this is supposed to take Abby’s mind off the distance between her and Blair, what she finds may bring her closer to her sister than she ever thought possible.