Ernest Opik suggested its existence in 1932, but it was the man who also showed that the stars nearer to the center of  the Milky Way rotate faster than the outer ones that made a coherent case for it in 1950.  
Ernest Opik suggested its existence in 1932, but it was the man who also showed that the stars nearer to the center of  the Milky Way rotate faster than the outer ones that made a coherent case for it in 1950.  Distant enough to be gravitationally influenced by other stars, it is composed of icy planetesimals spherically distributed around the Sun at a distance of 1 light year.  For ten points, what cometary source forms a cloud around the solar system many times bigger than the Kuiper Belt?
Ernest Opik suggested its existence in 1932, but it was the man who also showed that the stars nearer to the center of  the Milky Way rotate faster than the outer ones that made a coherent case for it in 1950.  
Oort cloud