The Andromeda Galaxy

This  is the Andromeda Galaxy, which I was lucky enough

 to take as part of the GCSE Astronomy that I do every

Wednesday evening at school

This is the Andromeda Galaxy (M31) which lies around 2.5 million light years away from Earth and it our closest spiral galaxy. Observations taken in 2006 by the Spitzer Space Telescope suggests that the Andromeda Galaxy contains around 1 trillion stars. The Andromeda Galaxy is estimated to be 7.1×10¹¹  solar masses. This means that the mass of the Andromeda Galaxy is 7.1×10¹¹ times heavier than the Sun. The mass of the Sun being approximately two nonillion kilograms. The value of this constant was found by Henry Cavendish in 1798 at the University of Cambridge. He did this with a torsion balance which is designed to measure very weak forces. The invention of the torsion balance is usually credited to Charles - Augustin de Coulomb who invented it in 1777.