We've seen all manner of optical illusions over the years, from human-looking dogs to rotating horses. Just when it feels like we've seen them all, a stunning accidental illusion crops up in space, discovered by none other than NASA.
The space agency took to Instagram to share an image captured by the Hubble and Spitzer space telescopes of a collection of galaxies known as Arp 142. It noted that two of the galaxies bear "an uncanny resemblance to a penguin guarding an egg" (see our pick of the best optical illusions for more mind benders).
