Viktor Sergeevich Safronov (Russian: Ви́ктор Серге́евич Сафро́нов) (born Velikie Luki; 11 October 1917 in Russia – 18 September 1999 in Moscow, Russia) 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.