The Sun

The Sun is huge! The Sun is a medium size star. The Sun is 1000 times larger than Earth and contains more than 99% of the total mass of our solar system.

Inside the Sun We can see the spots on Sun΄s surface. They are more cool (4500K) than the surface (5800K). The spots are disorders of the Sun΄s magnetic field. From the inside to the surface, the Sun contains the core, the radiative zone, the convection zone and the Photosphere, the only visible zone of the Sun. All the light of the Sun is coming from there. More outside are the Chromosphere and the Corona.

The flares in the chromosphere

The corona

Back to the core of the Sun

Atoms are very small

The atoms, Hydrogen and Helium

The <magic> fusion

Fusion stops the gravitational collapse

Thermonuclear fusion and Sun’s life Every second 564 millions tons of Hydrogen fuse into 560 millions tons of Helium in the core of the Sun. The <lost> 4 millions tons of matter converse into energy (radiation γ). This energy stops the Sun’s gravitational collapse. The fusion makes the Sun stable for many billions of Years.

The evolution of the Sun The Sun was formed 4,5 billions years ago and will exist other 4,5- 5 billion years. When all the Hydrogen in the core will be fused into Helium, the fusion will go on in a layer outside the core. The Sun will expand to Venus orbit. The surface temperature will drop, so the Sun will turn to a red giant.

The fusion in a red giant

The helium burning stage When the temperature in the core reach 100 million K the Helium will fuse into Carbon. At an outside layer Hydrogen will fuse into Helium. Now the star is loosing material through its very strong solar wind.

The death of the Sun The Sun΄s remain will be a white dwarf, a very dense object, 100.000K hot. A fast expanding planetary nebular will form around the dwarf. The matter of the planetary nebula will enrich the next stars generation with heavy elements. Except Hydrogen and Helium, all the other elements are made in the stars.

The H/R diagram

The activity of the Sun The activity of the Sun follows a cycle of 11 years. The magnetic field is trapped in the movement of the hot plasma. We can see many Sun spots when the activity of the Sun is high. The Sun spots also are related to flares and coronal eruptions, jets of fast plasma that can escape the Sun.

Minimum and maximum activity

The solar wind The solar wind are the particles of matter (mostly Hydrogen and Helium cores) from Sun΄s eruptions what are reaching Earth and the other planets. The magnificent northern lights are the impact of the solar wind to Earths magnetic field and atmosphere.

Chemical elements in the Sun We have discovered all chemical elements on the Sun. Hydrogen is the most common, also Helium, Carbon, Oxygen and Nitrogen. The elements heavier than Iron are very rare. The nebular the Sun is coming from was already enriched (from remains of stars that did belong to an earlier generation) in elements and complex molecules. This is typical for a star on the Galaxy disk.

Our Sun in the Galaxy

The solar eclipse The total solar eclipse is the most spectacular event we can see from Earth. It happens almost every Year, but only in a very small area on the Earth. The Sun is 400 times larger than the Moon, but also 400 times more far from Earth. So the Moon covers the Sun during the totality, and we can see the Chromosphere and the Corona, which are normally invisible.