Einstein (1905) E = m x c 2 (Energy equals mass times the square of the velocity of light) c = 300,000 km/sec c 2 = 9 x = 90 billion

The Sun shines for billions of years, because high pressures and temperatures in its very interior cause nuclear reactions to take place, converting hydrogen into helium and, in the process, some matter is converted into a huge supply of energy.

Bethe and Critchfield (1938)

Per second, the Sun converts 600 Million tons of H into He!

Hertzsprung-Russell diagram

Wien’s law max = 0.29/T

The maximum wavelength of the Sun’s emission is in the visible light range and corresponds to a black body temperature of 5,800° K.

Mass (in solar masses) vs. temperature: The life cycle of a main sequence star like our Sun.

Fate of the Sun in the distant future

Homework, GG 105, classes 1-5, for 5 points extra credit: 1.) Carbon is the sixth element in the Periodic Chart. Its neutral isotope of the mass of 14 has a)How many protons b)How many neutrons c)How many electrons 2.) Describe (list) the (simplified) nuclear reactions that make the Sun shine. Due September 11, no exceptions!