Caption: A posthumous portrait of Pierre-Simon Laplace (1749--1827)---looking very Napoleonic era (1799--1815).

Laplace was one of the outstanding mathematicians and mathematical astronomers of his era.

Among many other things, he was one of the early proponents of the nebular hypothesis of Solar System formation (Wikipedia: History of Solar System formation and evolution hypotheses: Formation hypotheses, Wikipedia: Pierre-Simon Laplace: Celestial mechanics).

Laplace made it through the French Revolution---unlike poor Antoine Lavoisier (1743--1794):

La Republique n'a pas besoin de savants ... (The Republic has no need of savants ...)
---Wikipedia: Antoine Lavoisier: Final days, execution, and aftermath, probably apocryphal.

Laplace did talk once at least with Napoleon (1769--1821), then styling himself First Consul of France. A probably completely garbled, but famous, version goes:

Napoleon: ... they tell me you have written this large book on the system of the universe, and have never even mentioned its Creator.
Laplace: I had no need of that hypothesis.
---Quotation from Wikipedia: I had no need of that hypothesis.

... 'And who is the author of all this!' Mons. De la Place wished to shew that a chain of natural causes would account for the construction and preservation of the wonderful system. This the first Consul rather opposed. Much may be said on the subject; by joining the arguments of both we shall be led to 'Nature and nature's God'.
---Quotation from Wikipedia: I had no need of that hypothesis.

Credit/Permission: Sophie Feytaud (active 1829--1850), 1842 (uploaded to Wikipedia by a Japanese Wikipedia contributer, 2004) / Public domain.
Image link: Wikipedia: File:Pierre-Simon Laplace.jpg.
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File: Astronomer file: pierre_simon_laplace.html.