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.
The first of the planets to be discovered was named after the muse of Astronomy (Urania). Uranus is also the name of Saturn's father. Uranus was discovered by William Herschel in 1781, though it had been mistakenly mapped in the past as a star.