Do you know who took these photos?

Today, we launch Parallax, a blog on the new and unexpected stories behind a photo. But sometimes, what we don’t know is the story.

We don’t know if the horizon across the water in these photos is approaching sunrise or fading to dusk. We don’t know who took these photos, or exactly when, or why — nor how their slide film transparencies ended up at a thrift store on Hull St. in Richmond, Virginia, where Richmond-based photographer Meagan Abell came across them.

We do know a few pieces of the story, like how many people shared Abell’s Facebook post on the photos (more than 21,000 to date) and where they were probably taken (Abell believes Dockweiler Beach in Los Angeles). We know the sheer volume of online theories they have inspired, from a man who claimed they are of Amelia Earhart, to a woman who demanded the photos from Abell, fully convinced they were of her grandmother and great-aunt. Hundreds of others have added their thoughts on Facebook, Twitter and Instagram, eager to imagine the photos’ journey from the camera to the Internet. “Everybody wants to be the one to come up with the answer,” Abell said.

Who is the woman in the blue dress, gazing away from the California shore? More than a month after Abell first posted the photos, this question is all we really know. But Abell says she will never stop looking. “I’ve been checking every single comment that I see, just in case,” she said. “Who knows what a lead will come from?”

Parallax \ noun \ par·al·lax \ˈpar-ə-ˌlaks. The word “parallax” describes the camera error that occurs when an image looks different through a viewfinder than how it is recorded by a sensor; when one camera gives two perspectives. Parallax is a blog where photographers offer the unexpected sides and stories of their work. Tell us yours or share on Instagram at #PBSParallax.