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.
He said that the atom is mostly open space. If the nucleus were 2 cm in diameter, the nearest nucleus of an adjacent atom would be 400 meters away. Thus lead is empty space at the atomic level! Subatomic Particles: Protons, neutrons and electrons are subatomic particles. In other words, they are particles that are smaller than the atom.