Curiosity 4 of 10
4. The Sun holds almost all the mass of the Solar System
About 99.8% of the entire mass of the Solar System is in the Sun. Planets, moons, asteroids and comets, all together, add up to only the small remainder.
A giant at the center
The Sun has about 333,000 times the mass of Earth. By volume, roughly 1.3 million planets the size of ours could fit inside it.
Of the remaining 0.2%, most belongs to Jupiter, which alone has more than twice the mass of all the other planets combined. Saturn comes second. Earth is only a small fraction of that remainder.
It is this enormous mass that keeps everything in orbit. The Sun's gravity holds the planets in place and reaches comets billions of kilometers away. It also compresses the Sun's core to the point of fusing hydrogen into helium, producing the energy it radiates.
Even so, the Sun is an ordinary star. There are much larger and heavier stars, and many smaller ones. It is roughly halfway through its life: it is about 4.6 billion years old and should remain stable for another 5 billion or so.
Every second, the Sun converts about 4 million tonnes of mass into energy through nuclear fusion. That sounds like a lot, but it is so small compared to its size that over billions of years the loss barely shows.
Did you know? The Sun is not really yellow. Its light is a mixture of all colors and, seen from space, it looks white. From Earth's sky it appears yellowish because the atmosphere scatters part of the blue light.
