Our sun always had a significant value in the mythology of nearly all big cultures, like the Egypt, the Aztec, the Indians and the Chinese. According to our state of knowledge the sun is a big bright glowing ball, which mostly consists of ionized gas. The sun is about 4.5 billion years old and is with a distance of 150 million km the nearest star to Earth. The next star – Proxima Centauri – is about 268 000 times further away. There are millions of similar stars in the Milky Way and billions of galaxies in the universe. Our sun makes life on earth possible. She is the motor of Photosynthesis in green plants and thus also the source of all our food and fossil fuels. The influence of the sun on our planet and their interaction is the cause for the seasons, affects the oceans, the weather and the climate.
The mass of the sun is 333,400 times greater than the mass of the Earth, which makes 99.86 % of the mass of our entire solar system. It is held together by gravitational forces that generate an immense inner pressure and the temperature at its core.
The core temperature is about 16 million °C, which is sufficient to maintain the thermonuclear fusion reactions. The released energy prevents the sun from a collapse and keeps its shape upright. The total energy released is 383 billion trillion kilowatts, which is about the energy released in an explosion of 100 billion tons of TNT per second.
The sun consists in addition to the energy-producing core of 2 distinct regions. The temperature increases on their way from the core through these two layers from 8 million °C to 7000 °C. The photons need on their way from the density of the core to the surface some 100,000 years.
The surface of the sun, the Photosphere, is the visible about 500 km thick layer from where light and heat are carried, and the place where sunspots are found. Above the photosphere lies the Chromosphere, which is visible during a total eclipse of the sun as a red ring and consists of hot hydrogen atoms. The temperature rises steadily with increasing altitude up to 50,000 °C, while the density decreases of 100 000 times from the photosphere. Above the Chromosphere is the Corona, which extends beyond the sun in the form of solar winds. The Corona is extremely hot with a temperature of several million degrees. Physically, an increase in the thermal energy from the cooler surface of the sun to the hot Corona is impossible. The source of the intense heat in the Corona is a scientific mystery for over 60 years. Scientists believe that the energy transfer takes place in the form of waves or magnetic energy. Similar results also brought the latest data from the SOHO and TRACE satellite observations, which provided the evidence of an upward transfer of magnetic energy from the solar surface to the Corona. NASA scientists are studying this mysterious phenomenon.
| Discovery date | unknown |
| Diameter | 1 391 000 km = 1.391 x 106 km Comparison: 109 x Earth |
| Circumference | 4 379 000 km = 4.379 x 106 km |
| Volume | 1 142 200 000 000 000 000 km3 = 1.1422 x 1018 km3 Comparison: 1 300 000 x Earth |
| Mass | 1 989 000 000 000 000 000 000 000 000 000 kg = 1.989 x 1030 kg Comparison: 332 900 x Earth |
| Density | 1.409 g/cm3 Comparison: 0.255 x Earth |
| Surface area | 6 087 799 000 000 km2 = 6.087799 x 1012 km2 Comparison: 11 990 x Earth |
| Surface gravity | 274 m/s2 Comparison: Someone with 100 kg on Earth, would weigh 2806 kg on the Sun. |
| Escape velocity | 2 223 720 km/h = 6.177 x 105 m/s Comparison: The escape velocity on Earth is 40298.5 km/h. |
| Sidereal rotation period | 25.38 Earth days 609.12 hours |
| Minimum/Maximum surface temperature |
5504 °C = 5777 K Comparison: The temperature of the Earth is ~ 185/331 K. |
| Spectral classification | G2V |
| Velocity (relative to average velocity of other stars in stellar neighborhood) |
19.7 km/s |
| Solar constant (entire solar radiation) |
1.365 – 1.369 kW/m2 |