An artist's illustration shows the grand scale of the Phoebe ring. (Credit: NASA/JPL-Caltech/Keck) Think you know what Saturn looks like? Think again: the planet's outermost ring is the biggest planetary ring known to mankind, but because its black color blends in with the blackness of space, images of the planet fail to capture it. Now, scientists examining the ring in the infrared spectrum say it's even bigger than they thought — by nearly one-third.