Questions & Answers
The sun is around 5,500 degress celsius. the most accurate method to measure the temperature relies on the fact that elements in the solar atmosphere absorb radiation, which wavelengths are absorbed and by how much also depends on the temperature
In 5 billion years, the sun will expand to become a ‘red giant’. It will engulf the planets Mercury and Venus, but the Earths fate is less clear. As the Sun swells up to 250 times its present size, it will lose more than a third of its mass to the strong stellar winds. This will cause the planets orbits to widen significantly so the Earth may just escape the out-rushing Sun. However at this point our planet will have been long dead, 3 billion years from now the Suns energy output will evaporate the oceans.