Saturn's Disappearing Rings
In 1610, Galileo first observed the rings of Saturn, which he saw as moons on either side of the planet because of his small telescope. Two years later, he was amazed to find that the rings seemed to have disappeared. Today we know that due to the tilt of Saturn's axis, our view of the rings changes. As Saturn orbits the Sun, the rings can sometimes be edge-on, making them nearly invisible from Earth's vantage point.