High Quality Content by WIKIPEDIA articles! Viktor Sergeevich Safronov (Russian: Viktor Sergeevich Safronov) (born Velikie Luki, Russia, 11 October 1917 - died Moscow 18 September 1999) was a Soviet astronomer who put forward the low-mass-nebula model of planet formation, a consistent picture of how the planets formed from a disk of gas and dust around the Sun.