The Kreutz sungrazers ( ) are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. A Kreutz sungrazer's aphelion is about from the Sun; these sungrazers make their way from the distant outer Solar System from a patch in the sky in Canis Major, to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion. Several members of the Kreutz family have become great comets, occasionally visible near the Sun in the daytime sky. The most recent of these was Comet Ikeya–Seki in 1965, which may have been one of the brightest comets in the last millennium. It has been suggested that another cluster of bright Kreutz system comets may begin to arrive in the inner Solar System in the next few years to decades. More than 4000 of smaller members of the family, some only a few meters across, have been discovered since the launch of the SOHO satellite in 1995. None of these smaller comets have survived its perihelion passage. Larger sungrazers such as the Great Comet of 1843 and C/2011 W3 (Lovejoy) have survived their perihelion passage. Amateur astronomers have been successful at discovering Kreutz comets in the data available in real time via the internet. Discovery and historical observations The first comet whose orbit had been found to take it extremely close to the Sun was the Great Comet of 1680. This comet was found to have passed just 200,000 km (0.0013 AU) above the Sun's surface, equivalent to around a seventh of Sun's diameter, or about half the distance between the Earth and the Moon. It thus became the first known sungrazing comet. Its perihelion distance was just 1.3 solar radii, that is, its perihelion was 1.3 solar radii from the center of the Sun, and just 0.3 solar radii above the surface of the Sun. Astronomers at the time, including Edmond Halley, speculated that this comet was a return of a bright comet seen close to the Sun in the sky in 1106. 163 years later, the Great Comet of 1843 appeared and also passed extremely close to the Sun.