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.
How did Democritus discover the atom? Quick Answer. Because ancient Greek thinkers such as Democritus lacked sophisticated technology and tools such as the microscope, his theory of the atom was due more to thought experimentation than to hard empirical observation, as used in modern science.