The sky is blue, grass is green, the sun is yellow. It's also probably ... It's the color of gloomy clouds and cuddly koala bears: gray. Or is it "grey"? Is "gray" or "grey" actually correct?

ForbesNASA Rover Makes Stunning Discovery Of Yellow Crystals On MarsBy Amanda Kooser Clouds on Mars vary seasonally. It’s currently autumn—a perfect time of year for cloudspotting—where ...