A Shining Example

Like most stars the Sun is a ball of incandescent gas comprised principally of the gases hydrogen (70%) and helium (25%). It is the conversion (burning) of hydrogen into helium which powers stars and makes them shine. Based on the famous discovery of Albert Einstein, that mass can be converted into energy (E=mc^2), the Sun shines by turning matter into radiation, primarily in the form of light. This, above all, is what makes the Sun a star. This process of generating light from turning hydrogen into helium in the solar interior is called nuclear fusion and is the same process as occurs in some nuclear power stations. In order for nuclear fusion to occur in a star its mass must exceed a certain value. A ball of gas will collapse under its own weight due to the force of gravity. If the total mass of gas exceeds about 1/10th the mass of the Sun then the interior will become very dense and very hot. These conditions are enough to trigger the nuclear conversion of hydrogen to helium. The energy released in this process is enough to make the gas turn into a shining star. The Sun's mass is approximately 10^30 Kg or about 333,000 times the mass of the earth. If the mass is below about 10^29 Kg, no nuclear reactions will take place and the gas will not shine but become something like a large version of the planet Jupiter, a giant gaseous planet. (Jupiter's mass is about 1/1000th that of the Sun).

Observing Stars

Star Menu