The distance to dead center there is 410 feet and that thing went far enough to splash into the fountain behind the walkway. Ridiculous.
The "true" distance of the prodigious shot was 489 feet, per ESPN Stats and Info (which measures how far the ball would've gone if the stadium didn't stop it), making it the longest home run this season.
The rest of the top five, via Home Run Tracker:
Stanton, by the way, has five homers that traveled at least 450 feet.