 The number and variety of prior speculations on the nature of the Kuiper belt have led to continued uncertainty as to who deserves credit for first proposing it.The first astronomer to suggest the existence of a trans-Neptunian population was Frederick C. Leonard.Soon after Pluto's discovery by Clyde Tombaugh in 1930, Leonard pondered whether it was "not likely that in Pluto there has come to light the "first" of a "series" of ultra-Neptunian bodies, the remaining members of which still await discovery but which are destined eventually to be detected".