Question: Who developed the modern model of the solar nebular disk instability model?
Disambiguated questions and answers: question: Who is thought to have developed the modern model of the solar nebular disk instability model?
Which geologist developed a planetesimal hypothesis that was a precursor to the modern model of the solar nebular disk?
Which astronomer developed a planetesimal hypothesis in 1905 that was a precursor to the modern model of the solar nebular disk?
answer: Soviet astronomer Victor Safronov
Victor Safronov
Thomas Chrowder Chamberlin
Forest Ray Moulton
Natural Questions answer: Victor Safronov (from the Wikipedia article "Nebular hypothesis")