A Very Common Star: One of 250 billion in our galaxy alone!

According to the latest estimates the universe is 13.7 billion years old. Our own star, the Sun is 4.5 billion years old. At present her distance from the Sun is approximately a 149.6 million km from the earth and it has a radius of 6960 km. It has a content of 1412 trillion cubic kilometres!

In fact our son is nothing more than one big nuclear fission reactor. Every second this gas ball converts 4 million tonnes of hydrogen into helium. In that process temperatures in the nucleus rise to 16 million øC. At the surface of the star that temperature is still 5500 øC.

In one second the Sun emits more energy than the entire mankind used during the past 300,000 years. Of all this energy the Earth catches only a 2 billionth of a part.

Our sun is not particularly special: the Milky Way, the galaxy of which we are part, counts about 250 billion stars. The entire universe consists of approximately 200 billion of these galaxies, 80 billion are estimated to be visible to the Hubble Space Telescope. That means that the number of stars in the universe is about 100 times greater than the number of sand particles on the beaches of earth!

Another 500 million years

During her existence the Sun went up approximately 25% in temperature. That is very common: As stars get older they burn this greater intensity. That also announces the demise of planet Earth. There are scientists who think that life on Earth will already be over in 500 million years. Because as the temperature rises, the earth will cook dry, just like Venus.

Our sun is only halfway her lifetime: she will quite certainly burn another 4 to 5 billion years. But after that there is the definitive end: she will swell up and first consume Mercurius then Venus and then probably the Earth. Next she will implode to a fraction of her original size. Ultimately a cold, dark and lifeless 'solar system' will remain.

Get another impression of the size of the universe from this clip: