Spinning planet(Science project)

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Spinning planet(Science project)

The Earth is like a giant ball spinning in the darkness of Space.

The only light falling on it is the light of the Sun glowing 150 million kilometers away.

The Earth turns once a day, and it orbits the Sun once a year.

The experiments on these pages investigate the two ways of moving, and explain why night and day, and the seasons, occur.

The ball represents the Earth and the torch the Sun.

In the final project, you can make a simple thermometer using water to record changes in temperature from night to day and from season to season.

Variable sunlight

The Sun’s light does not fall evenly over the Earth because our planet is round.

Imagine three identical beams of sunlight falling on the Earth. One falls on the Equator and the others on the North and South Poles.

The beam falling on the Equator covers a much smaller area, so its energy is more concentrated and the temperature Is higher.

YOU WILL NEED

Night and day: felt-tipped pen, plastic ball, piece of thin string, non­-hardening modelling material, torch.

Night and day

(1)

Draw or stick a shape on the ball to
represent your country. Stick the string to the ball with modelling
material.Tie the string to a rail, such as
a towel rail, so that the ball hangs freely.

(2)

Shine the torch on the ball. If the
country you live in is on the half

of the ball in shadow on the far side,
then it is night because it is facing
away from the Sun.

(3)

Your home country may be on the
half of the ball lit by the torch

instead. If so, it must be daytime here
because it is facing the Sun. Keep the
torch level, aimed at the middle.

(4)

Turn the ball from left to right. As
you turn the ball, your country will

move from the light half to the dark
half.You can see how the Sun comes
up and goes down as the. Earth turns.

Solar power

The Sun pours energy on to the Earth as heat and light.

The amount of energy received in any one place on the Earth changes with the seasons.

This is because the Earth’s axis is tilted. In summer, one half of the Earth tilts towards the Sun, and is warmer.

In the winter, it tilts away from the Sun and is colder.

The seasons

YOU WILL NEED

The seasons: felt-tipped pen, plastic ball, bowl just big enough for the ball to sit on, torch, books or a box to set the torch on.

(1)

Use the felt-tipped pen to draw a
line around the middle of the ball.

This represents the Equator. Sit the
ball on top of the bowl so that the
Equator line is sloping gently.

(2)

Put the torch on the books so it
shines just above the Equator. It is

summer on the half of the ball above
the Equator where the torch is shining,
and winter on the other half of the world.

(3)

Shine the torch on the Equator. It
sheds equal light in each hemisphere.

This is the equivalent of spring and
autumn, when days and nights are of
similar length throughout the world.

Make a thermometer

YOU WILL NEED

Make a thermometer: water, bottle, food colouring, clear straw, reusable adhesive, card, scissors, felt-tipped pen.

(1)

Pour cold water into the bottle until it is about two-thirds full. Add some food colouring. Dip the straw into the water and seal the neck tightly with reusable adhesive.

(2)

Blow down the straw to force
some extra air into the bottle.

After a few seconds, the extra air
pressure inside will force the water
level to rise up the straw.

(3)

Cut the card and slot it over the
straw. Let the bottle stand for a

while. Make a mark on the card by the
water level to show room temperature.
Take your thermometer outside.

(4)

On a hot day, the Sun’s heat will make the air and water expand,forcing the water level in the straw

above the room temperature mark.Cool the thermometer in the fridge. Mark the different levels.