The universe has so many dazzling sights that it seems silly to waste time on optical illusions. But some are just too amazing to ignore, like this shot of Saturn's moons Dione and Rhea seemingly morphing together into one mega-moon.

The two moons are actually separated by about a half-million kilometers in this photo, but an amazing combination of factors makes them look like one continuous object. Dione, the top moon in the image, was 1.1 million kilometers from the Cassini spacecraft, which took the photo, and Rhea was 1.6 million kilometers away. Because Dione has a diameter of 1,123 kilometers and Rhea is a bit bigger at 1,528 kilometers across, the two look to be the exact same size from Cassini's perspective.


The two also have a very similar albedo, or reflectivity, which means they appear to have the same amount of brightness. That helps them look like a single object, as does a crater on Dione's south pole. The large, faint crater Evander smooths over what would otherwise be a fairly obvious dividing line between the two moons, making it very difficult to tell where one ends and the other begins.