1. Sun is essentially a huge ball made of burning Hydrogen (roughly 75 %) fusing into Helium (roughly 25 %).
2. It has a mass of 330 thousand Earths and diameter of 110 Earths. Almost one million Earths could hypothetically fit into the Sun. Almost 99.9 % of the Solar system is contained in the Sun. The majority of the rest belongs to Jupiter.
3. It's 4,6 billion years old and will die after about 5 more billion years when all its fuel (currently burning at the speed of 4 million tons of Hydrogen per second) will be used. Before that it will expand to much bigger size, consuming the nearest planets, including Earth, by the way, then shrink up to the size of the Earth, still keeping the mass becoming a so-called white dwarf and eventually ending its life cycle as a black dwarf.
4. Virtually all energy on the Earth comes from the Sun. All our food and most of the fuel gives us energy thanks to chemical bonds made due to photosythesis or by living organisms eating food made by photosynthesis. A photon of energy needs about eight minutes to travel from the Sun to our planet, but it needed several million years to travel from the Sun's core to its surface.
5. Numerous religions on all continents of our planet worship or worshipped Sun. Egyptian Ra, Japanese Amaterasu, and Incan Inti are among most well-known examples. About 30 flags of countries in the world depict Sun.
6. It's about 25 million degrees Celsius inside the Sun. It's only huge mass of all the burning gasses preventing the Sun from the explosion. The surface of the Sun has only 5500 degrees Celsius.
7. The average distance between the Sun and the Earth (about 150 million kilometers) is called one Astronomical Unit (AU).
8. The solar system consists of the Sun, eight planets and five dwarf planets, as presented in the table below.
9. One day of the Sun (rotation around its axis) lasts about 25 Earth days. Its gravity is 28 times the gravity of the Earth.
10. Approximately every 11 years the Sun changes its polarity. Its north pole becomes south and vice versa. Sun's magnetic field is only twice bigger than Earth's but can be much more concentrated in some areas being about 3 thousand times stronger than Earth's.
11. The first suggestion of the Sun is actually a star comes from Greek philosopher Anaxagoras. First who claimed the Earth moves around the Sun was another Greek Aristarchus. Polish mathematician Nicolaus Copernicus was first who constructed a model of the Solar system in the 16th century as it's known today, but it was only after Isaac Newton supported it with his formulas in the 17th century when majority accepted his idea.
12. The distance from the Sun to the Earth is about 400 distances from the Earth to the Moon.
13. Exposure to the Sun's UV rays causes our skin to tan. These rays have antiseptic properties but would be deadly for us if the majority would not be absorbed by our the ozone layer in the higher altitudes our atmosphere.
14. Lights emitted by Sun are all colors, but we see it as white or as one of different colors through it changes thanks to atmospheric scattering (electromagnetic radiation is scattered by atmospheric particles). Typical change is the red color of the sunrise or the sunset.
15. The sun is closest to perfect sphere among all objects known in nature.
16. Like everything in Universe, the Sun moves too. It travels by 20 kilometers per second relative to other stars and about 220 kilometers per second around our galaxy (called The Milky Way). It comes around the galaxy in approximately 250 million years.
17. The Sun is only one of approximately 6 thousand stars visible by a naked eye and only one of approximately 200 billion stars in Milky Way, one of many galaxies in the Universe. According to surveys more than half (55 %), Americans know that sun is a star.
18. It's illegal to smoke a pipe after sunset in Newport, Rhode Island and it's forbidden to walk backward after the sunset in Devon, Connecticut.