Both Uses of

glimpse
in
The One and Only Ivan

All night I sat wondering about the gorilla I'd glimpsed.
p. 26.7

glimpsed = seen briefly

Sometimes, when we are lucky, we catch a glimpse of the moon through the skylight in the food court.
p. 77.4 *

glimpse = quick look

Definition:

a quick look or partial understanding

The exact meaning of glimpse can depend upon its context. For example:

"I caught a glimpse of her when I was walking to class." -- a very quick look
"I glimpsed at the headlines." -- looked quickly
"Reading the book gave me a glimpse of the life of a devout Muslim immigrant in America." -- a quick, incomplete view