Stranger Things fans think they've worked out how long season 5's time jump will be from a behind-the-scenes snap

We already know significant time will have passed when we reunite with Eleven and co in Stranger Things season 5, thanks to co-creators The Duffer Brothers  – but so far, the duo has kept pretty quiet on just how long said time jump will be. Now, though, a new behind-the-scenes snap has offered up a clue... in the form of David Harbour's facial hair.

In a bunch of snaps shared by Ross Duffer on Instagram recently, the actor can be seen laughing away on set. As fans note in the comments, he's not just sporting a big grin in the image, but a big ol' beard, too, which is an undeniable signifier of just how much time has passed since we last saw him...

If you cast your minds back to the season 4 finale, Hopper, Harbour's character, had just escaped from a Russian prison and had the buzzcut and five o'clock shadow to prove it. "That's at least six months of hair/beard growth," one viewer pointed out on the post, as another joked: "This is how we should all measure time from now on. 'According to Hopper's beard, it's... 3pm'."

"Hopper is supposed to be dead, so the beard could be a disguise," argued another, while there were a few who suggested the time jump would be lengthier than half a year. "Millie [Bobby Brown]'s BTS shows her with long hair. I think it's way longer than that, at least a few years," one noted, as another wrote: "Luca's watch from the last posts tell us it was Thursday, 11-2. 1989 matches up with the day". (In 1989, November 2 fell on a Thursday. If season 5 was still set in 1987, that day would've been on a Monday).

It's worth noting that there was an eight-month gap between events between Stranger Things' summer-set season 3 and season 4, so the time jump between the latter and season 5 will likely be substantially wider if the Duffers thought to specifically mention it to fans in advance. Harbour's beard looks much like the one he has in Black Widow, too, and he's currently filming Marvel follow-up Thunderbolts simultaneously in Atlanta, Georgia, so... we're gobbling up these fan theories with a pinch of salt.

Stranger Things is currently streaming now on Netflix. While we wait for more info on the fifth and final installment, check out our list of the best Netflix shows or our breakdown of all the cool new TV shows coming our way.