Every day we wake, arise, get out of bed, and go off to work, to school, or to play. And we do so with the assistance of the Sun, which gives us the power, the energy, the heat, and the light to exist. Indeed, if we want to think of an ultimate enabler in our lives from a scientific standpoint, then the Sun would be it. Life on Earth, of course, never would have been possible without the existence of our star.
Let's consider the Sun for a moment. We often hear that the Sun is an “average” star, an unspectacular, middleweight among countless numbers that are larger, more energetic, and more dramatic, or smaller, quieter, and longer lived. But is the Sun really an average star? What does that really mean? Moreover, we know the Sun is about halfway through its normal lifetime. What will become of our star when it runs out of fuel to burn? When will this happen? Will the Sun die slowly and quietly as the fuel runs out? Or is there a more spectacular fate in store?
Stars, of course, are plentiful in our galaxy and in the universe. And in our area of the Milky Way, our galactic neighborhood, things are pretty typical relative to other regions where stars are found. In the Milky Way Galaxy alone, astronomers believe about 400 billion stars exist. No one knows exactly because the abundant dwarf stars, so huge in numbers, are hard to detect over long distances because they are faint. Being the nuclear fusion reactors that they are, stars transform hydrogen into helium, and they emit huge amounts of radiation as a byproduct. They are nature's nuclear engines. As such, the Sun is a pretty good one. The Sun fuses roughly 700 million tons of hydrogen every second. That's the equivalent mass of 1.3 million fully loaded Boeing 747–8s.
The Sun is a spectral type G2V star, meaning it is whitish and is a so-called main sequence star, on the normal path of its evolutionary life, about midway from start to finish. The “G2” stands for the Sun's color-temperature classification, and the “V” means it's a main-sequence star. The Sun's spectrum peaks at yellow/green wavelengths, but the overall distribution of colors and intensities gives rise to what we perceive as “white light.” Indeed, sunlight is the definition of white light.