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.
In fact Neptune could have been discovered without the mathematical arguments. It very nearly was discovered by Galileo, the first person who could possibly have discovered a new planet. Galileo turned his telescope on the planets and was immediately fascinated by the system of Jupiter and its moons which he observed.