Mythology:
Many ancient civilisations worshipped the Sun as a god. In Egypt is was Ra, in Greece Helios and in Ancient Rome, Helios. The Celts had Lugh, the Aztecs had Tonatiuh and the Japanese believed in Amaterasu, the Sun Goddess. 

Composition:
The Sun consists of about 75% hydrogen and 25% helium by mass. The Sun is not a solid body like Earth. The outer layers rotate at different speeds. The Sun produces each seconds 386 billion billion megawatts of energy which is produced by nuclear reaction. The Sun emits 'solar winds' that are ejected by solar flares and can have powerful effects on Earth. These include simple power surges as well as the 'Northern Lights' ( aurora borealis ). The Sun is estimated to be about 4.5 billion years old. It is expected to 'live' for another 5 billion years until its energy is used up. This will result in a planetary nebula which will involve the destruction of the solar system.

Spiritual aspects:
According to Steiner, Sun activity mirrors the diastole (the filling phase of the heart) and the systole (the emptying phase of the cardiac cycle). This activity divides into two aspects: 'Winter Sun' (Night Sun) and 'Summer Sun' (Day Sun). Each phase is of primary importance when making preparations and the contracting and expanding Sun activity effects all life on Earth. Farm activities need to fit into these natural rhythms. 
Preparations 500 and 501 connect to this cosmic process. 500 (horn manure) is exposed to the 'Winter Sun' and 501 (horn silica) exposes to the 'Summer Sun'. The rhythmic vortex-like stirring of these preparations echoes the inward and outward pulsating of the heart and the Sun alike.

Some far out R.S. quotes on the solar system