The author of The Fault in Our Stars is having a big day. He’s on the set of his book-turned-film and has shared a couple of messages from the set.

John Green arrived on the Fault set early Monday morning where he met Ansel Elgort, who plays Augustus Waters, for the first time.

For his birthday (which was Saturday), Green was given a Fault in Our Stars movie clapper. He shared it on Instagram after getting into Pittsburgh on Sunday night:

Green also had his own trailer to spend the day in:

He shared a photo from within the set of Hazel’s house where they made bottles of Phalanxifor, a fictional tablet with molecules “designed to attach itself to cancer cells and slow their growth,” according to Green in his book.

Green’s assistant Rosianna shared a photo of his chair on the set:

And in his most recent tweet, Green admitted that the whole filmmaking experience has been very moving so far:

On Monday afternoon, Elgort shared a fun photo of him and Green on set:

The Fault in Our Stars officially began principal photography on Monday morning in Pittsburgh, Pennyslvania. Shailene Woodley stars as Hazel Grace and the film is directed by Josh Boone.

Late last week we shared with you a photo of Elgort and Woodley on set together in what can be considered our first look at Hazel and Augustus in the movie.

Source for all images: John Green’s Twitter.