Their hypothesis called for the close passage of another star to trigger this condensation, a concept that has since fallen out of favor.

In the first decades of the twentieth century, some additional small satellites were discovered to be in orbit around Jupiter.

... Moulton is today remembered as the author of several introductory books on astronomy, in particular his celebrated text on celestial mechanics; for his role in the formulation of the Chamberlin-Moulton planetesimal hypothesis; and for his work on ballistics in World War I.

It was in connection with his wartime work on ballistics that he developed the popular method of numerical integration which now bears his name.

His research on its periodic solutions began with his 1899 PhD thesis on oscillating satellites and culminated over 20 years later with the publication of his magnum opus the book Periodic Orbits (1920).In September of 1960, Katherine Johnson used Moulton’s book, An Introduction to Celestial Mechanics, to assist her in calculating how John Glenn would return safely to Earth after his orbital flight.