The immediate cause of sudden cardiac arrest is usually an abnormality in your heart rhythm (arrhythmia), the result of a problem with your heart's electrical system.
Version for printing. The first planet to be discovered was Uranus by William and Caroline Herschel on 13 March 1781. It was discovered by the fact that it showed a disk when viewed through even a fairly low powered telescope. The only other planets which have been discovered are Neptune and Pluto.
Pluto was discovered by Clyde Tombaugh in 1930, and was originally considered the ninth planet from the Sun. After 1992, its planethood was questioned following the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris, which is 27% more massive than Pluto, was discovered, which led the International Astronomical Union (IAU) to define the term planet formally for the first time the following year. This definition excluded Pluto and reclassified it as a member of the new dwarf planet category.