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LO: Modelling the relative movements of the Earth, Sun and Moon and how natural phenomena such as solar and lunar eclipses and phases of the Moon occur
The moon was created around 4 billions of years ago, from the Earth! Over 4 billion years ago the world was just begging to form. At this stage we call it proto earth. It was a huge ball of molten hot lava, when a Mars sized plant, called Theia, collided with it.
The debris released from the collision circled the earth and gave it a partial or full ring. One fragment was large enough to make a Proto moon. The proto moon began sweeping up the remaining fragments and over the next 100 million years grew, cooled and solidified into the moon.
Back in ancient times, it was thought that the moon produced it’s own light. Now days, we know this isn’t the case. Unlike the sun, the moon doesn’t create it’s own light, it instead reflects the light from the sun. The amount of light that is reflected, is based on the different phases of the moon.
As we said before the we only see one side of the moon from earth because the moon rotates at the same speed as it orbits.
However, even though you see the same side of the moon, you sometimes look up and see that there’s a full moon, half a moon, or a crescent moon. Even though you can’t see the whole moon we all know that the moon’s shape doesn’t changes.
So why is this?
When the moon is between the earth and the sun, it appears as if there is no moon, this is because it is reflecting all the light on its back. When it’s on the opposite side, it is a full moon, because it reflecting all the light on its face. This means that we only get a full moon once a month.
So, how does an eclipses work then?
The important thing to note first, is that there are 2 types of eclipses, Solar and Lunar.
A Solar eclipse occurs when a new moon passes in perfectly between the sun and earth, the reason a solar eclipse doesn’t happen every time is because the moon’s orbit is on a 5 degree tilt.
Making the chances for it to pass exactly in front of the sun rare.
We can have different types of solar eclipses. A total solar eclipse means the sun, moon and earth are perfectly aligned and the sun is completely blocked.
Partial solar eclipses occur when parts of the sun’s light is blocked. Only parts of the world can see a total solar eclipse.
A lunar eclipse is the opposite. Instead of the moon being between the sun and earth, the earth is between the sun and moon. So the Moon is behind the earth at this stage. The moon passes into the ‘Umbra’ or earths shadow, making it look red.
But why is it red?
Well, we know white light is made up of many different colours. As the light hits our atmosphere the smaller wave lengths of light, like blue, are scattered. Longer wave lengths, like red, are left over and reflect off the moons surface and down to us on earth.
This is the same reason why sun sets appear redish.