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.
Every now and then the moon still takes a beating from random asteroids. The great Imbrium Basin was formed by these collisions (seen to the left).
Scroll over the image
Lets fast forward to today
What role does the moon play for us?
The earth orbits the moon, and is the Earths only natural satellite. As it circles the earth over 27.3 days it slowly spins, taking 29.5 days to complete a full rotation. This is why we only see one side of the moon from earth.
You’ll often see at night how bright the moon is. This is because the moon reflects the light from the sun.
Tides
So you’ve probably heard that the moon controls the tides on earth, but how?
Gravity created by the moon and sun attract the water towards them.
As you can see in the animation to the left, when the moon and the sun are on the same side we have super high tides and super low tides. This is called Spring tides.
If we move the sun and moon to opposites (press #1), they give the same effects, Spring tides.
If we move the moon, but leave the sun (press #2), then we have normal high and low tides. This is because the sun pulls on the earth, is counteracting the effects of the moon, but its only ½ as strong because its much further away.
So if the moon is pulling the water towards it on one side, why is there a bulge on the other side?
This is because the moon doesn't just pull the water but the land as well. The water closest to the moon gets pulled the strongest, the land gets pulled a little less and the water on the other side gets ‘left behind’ and forms its own little lump.
The video bellow, illustrates how the moon came to be.
The full movie can be seen at:
https://www.youtube.com/watch?v=57merteLsBc
Phases
Sometimes you might look up in the sky and see that there's only half a moon, or a crescent moon, but wee all know that the moon is a circle and it never changes.
So why is this?
The animation to the left shows how the earth appears to us at various positions in the sun.
Scroll over the earth to see how it rotates
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.
To the left is a video of a solar eclipse which took place in Australia on 2012
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.
