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 polarizing beam splitter. The total system uses three 1k × 1k Sarnoff CCDs, two are used for direct narrow-band observations and the third is collecting simultaneous wide-band images. The "TRI-Port Polarimetric Echelle-Littrow" (TRIPPEL) is a Littrow spectrograph using a 79 grooves/mm echelle grating with a blaze angle of 63.43 degrees. TRIPPEL’s wavelength range is about 380-1100 nm, and it has a moderate resolution for a solar telescope, with R being approximately 200,000. This corresponds to about 1.3 km/s on the solar surface. TRIPPEL has a number of key useful features. It allows simultaneous observations at 3 different wavelengths, can in