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.
Since helium makes up about a quarter of the mass of the sun, it is not surprising that its presence was detected there over 100 years ago. What is perhaps surprising, is that helium was discovered in space 26 years before it was found on earth. It has been known for hundreds of years that certain elements impart characteristic colours to a flame-a fact crucial to the coloured fireworks that we enjoy.