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
Swedish Solar Telescope is evacuated internally to avoid disruption of the image from air inside. This is a particular problem with solar telescopes because of the heating from the large amounts of light collected being passed on to any air causing image degradation. As of 2005 the SST has produced the highest resolution images on the Sun of any telescope. This is largely thanks to its adaptive optics system, which was upgraded to an 85-electrode monomorph deformable mirror from CILAS in 2013. There are two modes of operation, selected by switching the beam from one optical table to another. One mode is a