National Geographic has published nearly 1500 covers in its 126-year run. Here are five of the best – and how they came to be.

Above: The eyes of Sharbat Gula, who would become known simply as "The Afghan Girl." Gula appeared on the cover of the June 1985 issue of National Geographic. Photographed by Steve McCurry, it is arguably the most famous cover in the magazine's history.

Here's the backstory on "Betsy," the border collie that appeared on the cover of March 2008's "Animal Minds" issue, and a "[superstar] of the animal cognition world":

Betsy, along with other animals featured in the story, like Azy the orangutan and Maya the bottlenose dolphin, are the superstars of the animal cognition world, photographer Vince Musi says.

To illustrate the story on animal intelligence, Musi chose to take their portraits rather than depict their behavior. As with human subjects, it took a little bit of coaxing and cooperation to get the perfect shot.

"I set the lights up, I try to sing to [the animals] a little bit, introduce them to some culture, often Frank Sinatra and sometimes Elvis Costello," Musi says in a video. "And I tell them everything I wanted to do."

Betsy, who was photographed in her hometown of Vienna, Austria, was one of the most cooperative animals Musi worked with, recounts photo editor Kathy Moran.

"After hours with the prairie dog, there was one usable shot," she says. By comparison, "Betsy was pretty easy."

More at National Geographic.