The Sun

Our sun. It is an amazing thing. Its presence holds the planets in the solar system, and it’s heat and light give life to the world.

The sun formed 4.567 billion years ago from the gravitational collapse of a molecular cloud.

Every second, more than four million metric tonnes of matter converts to energy. At that rate, it has already converted over 100 earth size masses to energy. It will spend around 10 billion years total as what is called a main-sequence star. Then it will become a Red Giant as it burns off hydrogen.

As the solar radius increases the Sun’s luminosity increases, approximately 10% every billion years.

In the next billion years, this increase will lead to the evaporation of all surface water on Earth, and the atmosphere will burn away. In temperature and appearance earth will be like Venus. Tidal forces will try to push the earth farther out, while gravity will pull it towards the sun. It is anyone’s guess which will succeed.

After becoming a Red Giant, the sun will spend the next 120 million years shrinking back to ten times its current size and 50 times the luminosity.

The sun will burn off helium, and once again expand. 20 million years it will grow, and collapse back again, becoming a White Dwarf. In this state will be the longest part of its life, as it will continue this way for trillions of years until finally fading to black.

It is a truly awe-inspiring and humbling thought.



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