The Sun

The big red ball of three-quarters hydrogen and one-quarter helium we call the Sun is omnipresent in our lives, but we cannot look up to it for very long, and we rarely think about its prominence and importance.

The diameter of the Sun is 1 390 000 km. In comparison, the diameter of the Earth is 12 700 km, and the distance from east to west in North America is around 3 000 km. The Sun contains 99.8% of the total mass of the Solar System (2*10^30 kg), and has the same volume as 1.3 million Earths.

There are around 8.5*10^37 fusion cycles per second at the Sun's core. To put this in perspective, our little microprocessor circuits right now function at around 3 billion operations per second - a mere 3*10^9. Concretely, this means that 4.4 million tonnes of material is consumed by the Sun every second, and consumes the equivalent of the Earth every 44 million years.

This is not to mean that we should worry immediately about the fate of our celestial big brother, since the Sun has a mass of 2*10^30 kg. Our familiar star is so gigantic that it takes a photon one million years to travel from its core to its surface, re-emitted from atom to atom, and then only 8.5 minutes from there to Earth.

The Sun will, however, eventually die, like everything else. A star is born when small disturbances in a scattered mass of gas and dust (called a stellar nursery) coagulates matter in accordance to the law of gravity. Eventually enough mass is accumulated and triggers fusion. In our galaxy alone there is more than a hundred billion stars.

However, as the Sun's fusion spends more and more of its material, it eventually densens and shrivel, no longer emitting enough heat for most forms of life. This has been traditionally seen as the end of life on Earth, and should happen in around 7.5 billion years. The clock to the right represents the Sun's life, and the green slice is the window of time when life on Earth is possible. We are already in the middle of this one billion years span.

There is no wonder that the Sun is the most inspiring and important entity in early religions. Sun-worship existed for the greatest period in our history (from the Neolithic to the Bronze Age, almost 3000 years) and, while few cultures had a full-fledged religion devoted to the Sun - mostly Egyptian, Indo-European and Meso-American cultures - it has been found worldwide.

Go To Page: 1 2

Articles in this Topic    Discussions in this Topic