Subrahmanyan Chandrasekhar calculated the mass limit for white dwarfs at age 19 on a boat to England

Chandrasekhar limit

Chandrasekhar limit is 1.4 solar masses

Henrietta Swan Leavitt

Henrietta Leavitt discovered the period-luminosity relation of Cepheid variables

Neutron stars are so dense that a teaspoon of their material would weigh about 6 billion tons

Neutron stars: teaspoon weighs ~6 billion tons

Sun

The Sun makes up 99.86% of all mass in the solar system

Periodic table

Dmitri Mendeleev arranged the periodic table by atomic weight and left gaps for elements he predicted would later be discovered

Footprints on the Moon (1975 film)

Moon footprints endure millions of years; no wind/water erosion