THE SOLAR SYSTEM BY MARIA DOMINGUEZ MARIA DOMINGUEZ

The solar system consists of the sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago.Of the many objects that orbit the sun, most of the mass is contained within eight relatively solitary planets whose orbits are almost circular and lie within a nearly flat disc called the ecliptic plane. The four smaller inner planets, Mercury, Venus, Earth and Mars, also called the terrestrial planets are primarily composed of rock and metal. The four outer planets, the gas giants, are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn are composed mainly of hydrogen and helium,the two outer most planets, Uranus and Neptune, are composed largely of ices, such as water, ammonia and methane, and are often referred to separately as ice giants. The SUN and the EARTH

The Milky Way is a barred spiral galaxy. This the galaxy is that contains the Solar system. The term milky way is a translation of the Latin for milky road. THE MILKY WAY

THE PLANETS The planets revolve around the Sun. They haven´t their own light but reflect sunlight. They have different movements. The most important are two: the rotational and the translational. For the rotation, rotating on it self around the axle. This determines the lenght of day on the planet. For the translations, the planets orbits around the sun.

THE SUN The Sun is the star at the center of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. Less than 2% consists of heavier elements, including oxygen, carbon, neon, iron, and others.

THE MOON The Moon is Earth's only known natural satellite and the fifth largest satellite in the Solar System. The Moon is the second densest satellite after Io, a satellite of Jupiter. It is in synchronous rotation with Earth.

THE EARTH The Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. The earth formed 4540 years ago, and life appeared on its surface within one billion years. The planet is home to millions of species, including humans. About 71 of the surface is covered by salt water oceans, with the remainder consisting of continents and islands.