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THE EARTHDiameter

Mass

Distance from the Sun

Days of Revolution around the Sun

Hours of Complete Rotation

Located far from the centre of the galaxy called the Milky Way is a relatively insignificant star which we call the Sun. Surrounding it is a collection of planets, moons and other objects which together form our solar system.

The Sun is a large ball of very hot gas, mostly hydrogen and helium. It is the power house of the Solar System. It's our nearest star.Scientists can tell what is going on inside a star from its color. Without the sun therewould be no life on Earth. We depend on the sun for energy.

With a diameter of 1 392 530 km, the Sun is a huge ball of gas. It has 333 000 times the mass of the Earth and is composed of 92% hydrogen, 7.8% helium and less than 1% heavier elements.

It is the source of all the light, heat and energy that is necessary to create and sustain life on the Earth.

THE SUN’S INTERIOR

Within the Sun there is a definite structure. Atthe centre and extending out to about a quarter ofthe Sun’s radius, is the core. Temperatures within thecore are approximately 15 million degrees celciusand it is here that all the energy of the Sun iscreated.

Diameter: 12 756 km Mass: 6.57x10Average distance from Sun:

149 597 900 km Orbital period: 365.256 days (1 year) Rotation period: 24 hr (1 day) Number of known satellites:

1 (natural), 7000+ (artificial)

24

Earth is the third planet from the Sun and isthe largest of the small, rocky, terrestrial-typeplanets. Of all the worlds in our solar system, it isunique in that the composition of its atmosphereand the presence of great oceans of water allowlife to exist and flourish on its surface.

HOW BIG IS THE EARTH?The Earth is 12,742 km in diameter. It's the

largest terrestrial planet in the solar system. TheEarth weighs 5,973,000,000,000,000,000,000,000kg. (That's nearly 6 trillion kilograms)

HOW OLD IS THE EARTH?Scientific evidence

shows that the Earth is4.6 billion years old.

Do you know that everyday and for oneyear we are travelling the distance of 940 millionkilometers at the speed of 107,000 kilometersper hour without leaving our homes and beingabsent from work or school?

Planet Earth functions as spaceship thatbrings us around the sun in the counterclockwisedirection (west to east). Such motion is calledrevolution and one complete journey the suntakes 365 ¼ days.

Perihelion is when the earth is closest to thesun in its orbit around the sun. This takes placeon January 3rd. The earth is 147 million km.away from the sun.

Aphelion is when earth is farthest from thesun in its orbit around the sun. This takes placeon July 4, the earth is 152 million km. swayfrom the sun.

WHAT IS ROTATION?Rotation is the movement of

the earth around its axis once in24 hours causing day and night.(diurnal motion)

THE EFFECTS OF ROTATION ARE :1. Parts of the Earth have day and parts of the

earth have night-results in the occurrence of dayand night.

2. It creates a centrifugal force which results in theshape of the earth, being an oblate spheroid(flattened at the poles and bulging at theequator.)

The effects of revolution are:

1. The change of seasons2. The varying lengths of day and night.3. The changing altitude of the midday

sun at different times of the year

1. The Earth spinning on its axis. Rotation

Revolution2. Going around a larger body. Rotation

Revolution

Revolution

4. Causes the Earth’s seasons. RevolutionRotation

5. Creates a year.

3. 24 hours. Rotation Revolution

RevolutionRotation

6. The moon going around Earth. RevolutionRotation

Diameter: 3476 km Average distance from Earth: 384 402 km Orbital period: 29 days 12 hr 44 min or 27 days 19 hr 18 min Rotation period: 27 days 19 hr 18 min or 28 days

The Moon travels around the Earth inan elliptical (oval shaped) orbit. Itsdistance from the Earth varies from356,000 km to 407,000 km.

Furthermore, having only one-eightieth of the Earth’s mass, means thatthe surface gravity of the Moon is justone-sixth of the Earth’s. This means that a60 kg person would weigh* just 10 kg onthe Moon.

The Moon has no atmosphere becauseits gravity is too weak to hold on to anygases it may originally have had. As a result,temperatures vary considerably from –184°C at night to 101 °C at noon. Since thepoles receive constant light and heat fromthe Sun, they have a constant temperatureof –96 °C.

Earth

Revolution

Planet

Earth

ROTATION or REVOLUTION