Astronomers use the principle of parallax to measure distances to the closer stars. Here, the term parallax is the semi-angle of inclination between two sight-lines to the star, as observed when the Earth is on opposite sides of the Sun in its orbit.
Ernest Rutherford discovered that atoms contain mostly empty space, with his gold foil experiment. Bhor discovered that the electrons are not randomly placed around the nucleu â¦ s.
Rutherford suggested the atom had a dense positively charged nucleus which occupied little space and that there was much empty space in the atom where the elctrons floated in a circle around the nucleus///Bohr suggested that there were rings which each held a specific amout of electrons and were held together by the force of attraction.