Colonization of the inner Solar System Colonization of the inner Solar System Bodies in the inner Solar System have been considered for terraforming and space colonization. The main candidates for colonization in the inner Solar System are Mars and Venus. Other possible candidates for colonization include the Moon and even Mercury. The short distance between the Earth and the Moon makes it a natural expansion after Earth. A number of government space agencies have periodically floated lunar plans such as Russia (2014), China (2012) and the US have made plans in constructing the first lunar outpost. The European Space Agency (ESA) head Jan Woerner has proposed
Discovery and exploration of the Solar System Domenico Cassini later discovered four more moons of Saturn and the Cassini division in Saturn's rings. Edmond Halley realised in 1705 that repeated sightings of a comet were recording the same object, returning regularly once every 75–76 years. This was the first evidence that anything other than the planets orbited the Sun. Around this time (1704), the term "Solar System" first appeared in English. In 1781, William Herschel was looking for binary stars in the constellation of Taurus when he observed what he thought was a new comet. Its orbit revealed that it was a new planet, Uranus, the first