The Sun

The Sun is the center and the star of the Solar System. The Sun is the most brightest object in the day and a natural heat source.

## Overview

Over the course of human history the Sun has been feared and worshipped. Rightfully so. What our ancestors knew on a fundamental level was that the Sun provides a vital ingredient for most of the life on Earth. Without the energy provided through sunlight, vegetation cannot grow, and without vegetation animals do not have a source of nourishment. However, what we know today that our ancestors did not is just how far reaching the scope of the Sun's influence is.

As our scientific knowledge has increased so too has our understanding that the Earth is merely a piece in the larger structure we know as the Solar System. What we have also discovered is that although other planets and bodies in the Solar System may not possess life, the Sun is just as influential to them. The Sun is what is known as a main sequence star; that is, a sphere composed primarily of the two gases hydrogen and helium such that certain conditions are met. The first condition is that it must have a mass falling within a certain range. Though debated, this range is generally accepted to be between approximately 1.4 x 1029 kg and 3.0 x 1032 kg. (This range is often describe as at least 75 times the mass of Jupiter and no more than 150 times the mass of the Sun itself.) The second and most important condition is that nuclear fusion must be present. Nuclear fusion is the process whereby two lighter atomic nuclei join or “fuse” together to produce a heavier atomic nucleus. In the context of stars, hydrogen is the lighter and helium the heavier.

The size of the Sun compared to the largest known stars (Red Giants) is not very big. However, if compared to the most common type of star in the universe, the red dwarf, the Sun is quite a bit larger. Thus, the Sun is not the biggest type of star in the universe, but it is definitely larger than most.

As far as the Sun’s mass compared to other bodies found in our solar system, the Sun is easily the most massive. The Sun alone contains 99.8% of the total mass in the Solar System. In terms of size, the Sun has a diameter of roughly 1.4 million kilometers (870,000 miles). To put this in perspective, this is almost 110 times the diameter of the Earth. What this means is that about one million Earth’s could fit inside the Sun**.** It has a mass of around 330,000 times that of Earth. It is three quarters hydrogen and most of its remaining mass is helium. Over one million Earth’s could fit inside the Sun. If you were to fill a hollow Sun with spherical Earths, somewhere around 960,000 would fit inside. However, if you squashed those Earths to ensure there was no wasted space then you could fit 1,300,000 Earths inside the Sun. The surface area of the Sun is 11,990 times that of Earth. One day the Sun will consume the Earth. The Sun will continue to burn for about 130 million years after it burns through all of its hydrogen, instead burning helium. During this time it will expand to such a size that it will engulf Mercury, Venus, and Earth. When it reaches this point, it will have become a red giant star.

Although we think of our Sun as a unique celestial body, it is, in fact, one of trillions of stars in the universe. On top of this, the Sun is rather ordinary as far as stars go. The official classification for our Sun is G V star (often referred to as a Yellow Dwarf star), which means that it is a main sequence star whose surface temperature is between 5027°C and 5727°C.

Some estimates for stars similar to the Sun in the Milky Way galaxy alone are as high as 7 billion. If this number is correct, there could be over one trillion stars that are roughly the same as our Sun in the universe.