'Back to the Future' Cast Reuniting For First Time Since 1989

Today's not just a huge day for "Back to the Future" loving nerds, it's also a huge day for their idols.

We're told Wednesday night will be the first time in more than 25 years the entire 'BTTF' cast will be together in the same room! They're all showing up for a screening at the Lincoln Center in NYC.

Of course, Oct. 21, 2015 is the date Marty and Doc travel back to in 'BTTF2.'

Claudia Wells, better known as Marty's girlfriend Jennifer Parker from the first film, tells TMZ even though she sees some of the cast at convention appearances from time to time ... the whole gang hasn't been together since the 1989 premiere of 'BTTF2.'

Wells already scored a bonus. She was expecting Marty, Doc Brown, Lorraine, Biff and even Mayor Goldie Wilson at tonight's screening -- but tells us she just ran into Huey Lewis in her hotel lobby Wednesday morning!

That's the power of love.