•The Solar System•The Sun•Planets and satellites•Asteroids•Comets•Movement of the Earth•The rotation of the Earth

•The seasons•The movement of the Moon•Lunar phases•Eclipses•Stars•Constellations•Nebulae•Galaxies

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The Solar System consists ofthe Sun, eight planets and their Moons, comets and asteroids. They are all called celestial bodies. Everything in the Solar System orbits the Sun.

The Sun is the largest celestial body. It is much bigger any planet. It is at the center of the Solar System.The Sun is an enormous yellow star witch provides the light and heat necessary for life on Earth. The Sun rotates on its own invisible axis.

• There are eight large celestial bodies called planets.

• Each planet rotates on its own invisible axis.

• Each planet also orbits the Sun.

• The planets can be classified into two groups: – Terrestial and Gas Gigant.

Mercury, Venus, the Earth and Mars are terrestial planets. The are small, and mainly made up of rock.

Jupiter, Saturn, Uranus and Neptune are called gas giants because the are large and are made up of gases.

Natural satellites: are smaller celectial bodies, such as moons, which orbit their planet.

In the Solar System, there are

thousands of tiny,

rocky celestial bodies calles

asteroids. They have

different shapes.

Comets are small celestial bodies made up of ice. They have bright tails which point away from the sun. We can only see the tail of a comet when it is close to the sun.

The earth revolves around the sun.

Its orbit is an elongated circle, called an ellipse.

The Earth takes exactly 365 days and six hours to complete its orbit. Our `normal` calendar years are only 365 days long

The Earth is a sphere.It rotates on its own invisible axis, wich passes throught the North and South Poles.

It takes twenty- four hours to complete this rotation.

At any time, one half of the Earth is facing the Sun. In that half, it is day. The other facing away from the Sun. It does not receive sunlight.

In that other half, it is night.

The Earth always rotates in the same direction. Consequently, the Sun always rises in the east and sets in the west.

The Earth’s axis is slightly tilted. At any time, one hemisphere is tilted to wards the sun, and receives more light and heat.

It is summer in this hemisphere. The other hemisphere is tilted

The Moon is the Earth’s only natural satellite.It take 27.3 days to orbit the Earth.

The Moon rotates on its axis in the same time it takes the Moon to orbit The Earth.

The same side of the Moon always faces the Earth.

Den we look at the Moon from Earth, its appearance changesthroughout the lunar month. These changes in appearance are called lunar phases. Each lunar phase depends on the Moon`s position in relation to boththe Earth and the Sun.

New Moon: No part of the Moon is visible because the side of the Moon facing the Earth is not being lit by the Sun.

First quarter: one half of the moon is being lit by direct sunlight.This illuminated half is increasing.

Full Moon: the side of the Moon facing the Earth is being lit by theSun.

Last quarter: the other half of the Moon is being it by direct sunlight.This luminated half is decreasing.

During a solar eclipse, the Moon passes between the Earth and the Sun, blocks the Sun’s light, and projects a shadow on the Earth.

When the Moon and Sun are in a perfect line, it is called a total eclipse.

A stars is a spherical body wich generates light and heat though nuclear reactions. Most stars consist of the gases hydrogen and helium. Stars have different characteristics.

Stars are divided into eighty-eight groups or constellations to make identification easier. The constellations have the names of characters from classical mythology or the names of animalsand objects because of the they form.

Colour: depending on their temperature, stars can be red, orange, yellow, white or blue.

Size: all stars are enormous, but some are largest than others.

Luminosity: this refers to the amount of light from the stars wich reaches the Earth.

Some constellations, such as Ursa Major, can be seen all year. However, Orion, for example, can only be seen in winter, and Hercules can only be seen in summer.

Galaxies are enormours groups of stars, gases and dust.

There are three types: elliptical, spiral and irregular.

Our Solar System is on the edge of a galaxy called the Milky Way.

All the stars wich we can see belong to this .