An absolute classic! Was just telling a buddy about this one the other day while talking about The Egg by Andy Weir (another short story I really enjoy). Every time I read this one, I get chills at the end. Asimov really was a master.
It's amazing that in the late 1930's, someone with his academic credentials and intellect decided his life would be best spent writing science fiction.
Totally agree, that ending sticks with you for a long time. Asimov had a way of making simple ideas feel massive.