I've seen the same planet colored differently in different photos. Here are the true colors of major planets to the best of my knowledge (spacecraft photos appearing in the media often have false coloration): Mercury: grey; Mercury has practically no atmosphere, so we just see the rocky surface.
Sitting for hours can cause poor circulation which is a major cause of the heavy legs syndrome and if there no underlying medical condition and the feeling worsens when walking upstairs, then curiously enough, you might like to look at your diet for clues.
Muscle fatigue or strain is the most common cause of leg soreness. Usually, a muscle strain happens from increased activity and causes a minimal amount of soreness. The soreness is easily relieved by rest and cold or warm compresses.