Sunday, May 09, 2010

Focus On: The Sun


The Sun
I decided the website needed more in depth detail regarding the workings of our Solar System. We start or journey at the heart of our solar syatem - THE SUN.
The largest star, at the centre of our solar system, at a distance of 92.96 million miles from Earth. This distance is known as an astronomical unit (or AU) and is used for measuring distances across our solar system.

The Sun, a monstrous sphere of mainly ionized gas, supports the life on Earth, as well as spreading light and heat across our solar system.
The Sun doesn't have a definite boundary like other planets, and in the outer parts density of its gases drop with increasing distance from its centre. However, it does have a well-defined interior structure (pictured and detailed below).
The core is the hot, dense central part in which the nuclear reactions take place. This is about 25% of the interior radius.
The radioactive zone is where the main transport of energy takes place (as well as the core) by photons (electromagnetic radiation). It is about 25% to 85% of the core radius.
The convective zone starts at around 85% of the core to just below the surface. It is a region where the change in temperature is so rapid that the Sun becomes unstable to convection - much like the Earth's atmosphere becomes convectively unstable on hot days, producing thunderstorms
The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and its energy escapes the Sun entirely. The photosphere is tens to hundreds of kilometers thick
The connections between the Sun and Earth are what drives our seasons, weather, climate and ocean currents.
Life Without The Sun?

Without the Sun we would, to put nicely, be screwed. For a start without the Sun, the Earth wouldn’t even exist. With no Sun the earth would be a cold
rock with no life and would simply be stationary as it would have no star to orbit.

If the Sun died out all life would probably die as there would be no sunlight.

The Earth would slip out of orbit and asteroid belts would be thrown into us and other planets, as well as orbiting Earth and other planets.

Earth may slip into the orbit of Jupiter.

Earth would no longer be considered a planet as it would no longer be orbiting a star.

Eventually Earth and the other planets would slip into the orbit of other stars but this would be over a period of millions of years.

Of course, all of this is just theory, as with no Sun we would all die and would never see this happen!

The fact is, the sun has been converting 7000 million tons of hydrogen into helium every second (releasing enormous energy that makes the sun shine), for 4.5 billion years. It is also expected to continue doing so for a similar length of time, so we don't need to worry about life without it - at least not in this lifetime.