I mages brought back from the spacecraft Magellan show the highlands regions that are above 2.5 km (1.5 miles) are unusually bright. This is a common characteristic of moist soil, but no traces of water have been found on the surface of . Scientists have come up with a few theories to explain these bright spots. One theorizes that these might be composed of metallic compounds, like "fools gold" (iron pyrite) which is known to be very reflective. It is very possible that this is a type of exotic material that doesn't exist on Earth.