What's outside the window?

In a 1998 novel by Chilean author Roberto Bolaño - "The Savage Detectives" - I found these visual riddles. The last one doesn't have a solution in the book, so I would like to know what you believe is outside the window.

The riddles appear in the last part of the book, which is written like a diary.

Here's the first one:

• What's outside the window?
• A star

The second one:

• What's outside the window?
• A sheet

And, finally, the third one:

So, what do you think is outside the window?