Professor Aurora Sinistra is one of the lesser-known members of faculty at Hogwarts. She appears a few times in passing but does not take a super active role. One of the things we know about her, though, is that she teaches astronomy in the tallest tower at Hogwarts, which led me to believe that she would be a fan of a big, cozy cardigan. It must get chilly on top of that tower!
This cardigan is so big and cozy that it might also be used as a coat! Especially if you use a looser-knitting yarn like the Classic Elite Yarns Bam Boo that I used to make the blue one pictured here.