If we weigh the entire Solar System, it turns out that our Sun contains about 99.87% of all the matter. This is equivalent to about 333 000 Earths.
The Sun will become a Red Giant in about 7.7 billion years. The radius will increase by 256 times, and the outer layers of the star will reach the current orbit of the Earth.
The total mass carried away from the Sun by the solar wind is huge. Thus, the Sun loses in 150 million years a mass equal to our entire planet.
If the Sun could be compressed into a black hole, its radius would be slightly less than 3 km. (In contrast, the Sun's radius is about 700,000 km) This is called the gravitational radius (or Schwarzschild radius).
Sunlight takes about 8 min to reach Earth, but photons can take thousands to millions of years to journey from the Sun's core to its surface. It all depends on the random "path" that the photon travels.
The "solar wind" is constantly blowing from the surface of the Sun - a stream of charged particles that released from the corona of a star. For this reason, the Sun loses millions of tons of mass per second.
Every 11 years, the Sun's magnetic fields reverse. North becomes south and south becomes north. For a full cycle of 22 years, the poles return to their original position. This process is very stable and is called "Hale's Law".
About 73% of the Sun's mass is hydrogen, and another 25% is helium. So, there is very little left for the rest of the elements (oxygen, carbon, iron, neon, nitrogen, and others).
The temperature in the Sun's core is about 15 million degrees Celsius, while on the surface it is only 5500°C. The core is much
hotter because it is where nuclear fusion reactions take place.
The Sun is gradually getting hotter and brighter. In about 1.1 billion years from now, our star will become 11% brighter. Life on Earth under such conditions can only survive in the depths of the oceans at best.
On our blue planet Earth, sunsets look red. But on Mars, which we used to call the red planet, the setting sun will be bluish.
Light from the Sun reaches Earth an average of 8 minutes and 19 seconds. It takes an average of 4 hours for light to reach Neptune, the last planet in our solar system!
The Sun's mean diameter is about 1 391 000 km. It is so vast that approximately 1.3 million Earths could fit inside it, or you could line up 109 Earths across the face of the Sun.
Our Sun is classified as a yellow dwarf main-sequence star, representing approximately 10% of the total stars in the Milky Way. Red and orange dwarfs, however, are much more common.
At the end of its life cycle, the Sun will shed its outer layers and transform into a dense type of cooling star (white dwarf). While there will be no more energy production through fusion, it will continue to glow and emit heat from its previous fusion for trillions of years.
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