Uranium, a silvery white metal, was isolated in 1841 by French chemist Eugene-Melchior Peligot (1811–1890) and named after the planet Uranus. Later, in 1896 French physicist Antoine Henri Becquerel (1852–1908) , showed that uranium salts and uranium were radioactive and, hence, discovered radioactivity for which he received the Nobel prize in 1903 sharing it with the French husband and wife team Marie Sklodowska-Curie (1867–1934) and Pierre Curie (1859–1906) who also made huge contributions to the study of radioactivity., There are three naturally occurring isotopes of uranium (uranium has eight isotopes in all): uranium-238, uranium-235, and uranium-234, which have half-lives of 4.6 billion years, 700 million years and 25 million years, respectively. The long half-life of uranium-238, which is close to the age of the Earth, means that it is by far the most abundant isotope (99.27% of any natural uranium).