Weighing a star

Weighing a star isn't as difficult as it sounds as you don't need an enormous set of cosmic scales, just one equation. The more massive a star is, the more energy it gives off. So first of all, astronomers measure the star's 'luminosity', the rate at which it emits energy. Then they can work out its mass.Measuring a star's temperatureOnce the mass of the star is known, you can calculate the temperature inside its burning core. Stars perform a delicate balancing act between gas pressure pushing outwards and gravity pulling inwards. Mathematical equations can be used to map this. Then by measuring the size and mass of the star, astronomers can calculate the temperature of the core.