Titan has no known magnetic field, and sometimes orbits outside Saturn's magnetosphere. This exposes it directly to the solar wind, which may ionize and remove particles from the atmosphere. In 2004, the Cassini probe arrived at Saturn and dropped a probe called Huygens into Titan's atmosphere. It landed and sent back images of the surface as well as measurements of Titan's atmosphere. Cassini was then able to map Titan's surface using radar, as was done on the Magellan mission to Venus. As amazing as these images were, they only posed more questions than answers. But thanks to Cassini, we have now witnessed some of the most detailed images yet of the ringed planet and her moons. Because Titan has a thick atmosphere containing hydrocarbons, scientists had long theorized that there could be lakes of liquid methane and ethane on its surface. When the Voyager spacecraft encountered Titan in 1980 and 1981, they were unable to see beneath the moon's thick layer of clouds. NASA's Cassini spacecraft arrived at Saturn in 2005 armed with radar. The radar instruments were able to see through the clouds and map the moon's surface. Radar images taken in 2006 proved the existence of liquid lakes on Titan. These are the first liquid lakes seen anywhere in the Solar System besides Earth. The largest of these newly discovered lakes is larger than the Great Lakes on Earth. In addition to the lakes, channels resembling rivers were observed. This provided strong evidence of liquid rain. Scientists believe that rain composed of liquid methane and ethane regularly falls across Titan's surface. In fact, the weather on Titan may be very similar to weather patterns on Earth.