Not that they don’t have a tough-enough leader in Marcus Pimpleton already, but … imagine the pressure of hitting the right notes when Darth Vader is wielding the baton! The Chief Sealth International High School Band had a surprise guest conductor for a few minutes during their mini-concert this morning at the Pacific Science Center grand opening of “Star Wars: Where Science Meets Imagination.” We reported on Thursday about the band’s downtown gig to celebrate the Science Center opening the doors for the first ticketholders to the new exhibit; after they played a medley of key themes from the entire “Star Wars” movie series, an entourage of familiar characters made their entrance, including Lord Vader. (They’re from the 501st Legion – explained here; right after the opening event with the Sealth band, they paraded over to the new exhibit, posing for photos – which their leader had explained is part of the deal in exchange for the costuming help they get from Lucasfilm!)

ADDED 2:04 PM: The band’s performance of the “Star Wars” medley, WITHOUT Darth Vader. That’s above; click ahead, and after the jump you will find the section of the encore that featured the Dark Lord of the Sith, plus a few more photos from this morning’s event:

That’s the section where Lord Vader stepped in – otherwise, as far as we could tell, it was the same medley, replayed. Here’s a look at a few more of the costumed participants from the 501st:

Here’s Bryce Seidl, Science Center CEO, speaking to the audience about the new exhibition:

And a slightly wider perspective of the scene:

This was a one-time-only gig for the Sealth band so far as we know but the exhibit will continue at PSC through May 8th.