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The sun and the planets Central star The Sun.

The Sun is the unique and central star of the Solar System; therefore, it is the star nearest the Earth and the star with greater apparent brightness.

Their presence or its absence in the terrestrial sky determines, respectively, the day and the night.

The energy broadcast by the Sun is taken advantage of by the photosynthetic beings, who form the base of the trophic chain, and is for that reason the main energy source of the life.

Also it contributes the energy that maintains in operation the climatic processes.

The Sun is a star that is in the denominated phase main sequence, with a spectral type G2, that formed about ago 5000 million years, and will approximately remain in the main sequence other 5000 million years.

In spite of being a star median, she is the unique one whose circular form can be appreciated at first, with an angular diameter of 32 ' 35” of arc in the perihelion and 31 ' 31” in the aphelion, which gives an average diameter of 32 ' 03”.

Accidentally, the combination of sizes and distances of the Sun and the Moon with respect to the Earth, cause that they are seen approximately with the same apparent size in the sky.

This allows an ample range of different solar eclipses (total, annular or partial).

There are shortage planetary systems that they have more than a central star (stellar system).

Planets The eight planets that compose the Solar System are, of minor to greater distance with respect to the Sun, the following: Venus Tierra Marte Júpiter Saturno Urano Neptuno mercury The planets are bodies that turn forming orbits around the star, have sufficient mass so that his gravedadsupere the forces of the rigid body, so that they assume a form in hydrostatic balance (practically spherical), and have cleaned the vicinity of their planetesimal orbit (orbital dominance).

The inner planets are Mercury, Venus, the Earth and Mars and have the solid surface.

The outer planets are Jupiter, Saturn, Urano and Neptune, also gaseous planets are denominated because they contain in his atmospheres gases like helium, hydrogen and the methane, and does not know with certainty the structure their surface.