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
A Beautiful Planet found to be orbiting within its star's habitable zone, or orbital area where liquid water could conceivably exist without freezing or vaporizing. In other words, it was the first discovery of an Earth-sized planet on which life could reside. The "Kepler" in this exoplanet's name comes from the fact that it was discovered by the Kepler Space Telescope, or "NASA Discovery Mission Number 10," a spacecraft observatory which is designed to find exoplanets in our region of the Milky Way Galaxy that are Earth-size and smaller, and that are within the habitable zone. The planet orbits Kepler-186, a red dwarf