An Alderson disk is a hypothetical artificial astronomical megastructure, similar to the ring in Larry Niven's Ringworld and the Dyson sphere. The disk is a giant platter with a thickness of several thousand kilometers. The Sun rests in the hole at the center of the disk. The outer perimeter of an Alderson disk would be roughly equivalent to the orbit of Mars or Jupiter. A big enough disk would have more mass than its Sun.