The Sun --> through 93 million miles of space, in about 8 minutes --> through the Earth's atmosphere --> through the glass window into your house --> through a little more air, inside the room --> through the glass fishtank --> through some water --> light hits the fish; all colors of light except yellow get absorbed by the fish; the yellow waves bounce off --> through the water again --> through the glass tank again, out into the room --> through some air again --> a little bit of the yellow light happens to go into your eye, and you see it. Most of it doesn't, though.