The internet loves a good challenge, like finding what's wrong with this brick wall or tracking down a camouflaged cat. The space equivalent of this sort of optical test is finding the tiny Saturn moon, locating a Mars rover or, now, spotting an cosmonaut's legs during a spacewalk. 

NASA astronaut Mark Vande Hei posted a photo on Twitter from last week's Russian spacewalk outside the International Space Station. He challenges us to find the spacewalker's legs and it's not easy. Check out the photo and make sure to enlarge it before you look. 

The photo shows a fetching view of Earth, some portions of the space station and, yes, the legs of a Roscosmos astronaut. 

Cosmonauts Alexander Misurkin and Anton Shkaplerov spent over eight hours outside the ISS during a spacewalk on Feb. 2, setting a new record for the longest Russian spacewalk. The pair installed components for an antenna to improve communications with Russia's flight controllers on Earth. 

Are you still looking? Here's a hint: Check toward the center-top part of the photo. Once you've located the legs, take a moment to feel impressed by the size of the ISS relative to the cosmonaut's lower limbs.