Astronomy Question Of The Week: How Long Will The Sun Continue To Shine.

Byline: Staff Writers

Bonn, Germany (SPX) Jul 07, 2009, 2009 A shining and 'well functioning' Sun is critical for our survival on Earth. The Sun was formed almost five billion years ago. At that time, a gas and dust cloud became so condensed due to its own gravity that hydrogen nuclei began to merge with each other and release huge amounts of energy in a process known as nuclear fusion.

Fortunately, the Sun's supply of hydrogen is so great that it will continue to shine for another five billion years. However, the intensity of the solar radiation will increase in the future and this will be fatal for life on Earth. As early as two to three billion years from now, the oceans will evaporate and it will become impossible to live on Earth.

On approximately its ten-billionth birthday - that is, in around five billion years from now - the hydrogen supply in the core of the Sun will be exhausted and the generation of energy will shift to the outer layers. As a result of this change, the Sun will expand and become a red-coloured giant star that engulfs the planets closest to it - Mercury and Venus.

As a 'Red Giant', our Sun will lose a considerable amount of mass - by expanding sharply, the gravitational force at its surface will decrease and, unlike now, a lot of solar matter will pour into space. As its mass reduces, the planets will not be attracted to the Sun as strongly as at present and their orbits ...