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1. This is a difficult concept. Hubble’s ‘Red Shift’ theory came about when he noticed that the red shift from distant stars was related to their age. This gave us another method for deciding the ages of very distant stars and galaxies. Red shift is a bit like the Doppler effect - when an ambulance is coming towards you , you hear its siren on a particular note. As it passes you the note changes - this is the Doppler effect.
Red shift is a similar thing with light. (background image)
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2. The ‘Big Bang’ theory is an attempt to explain the beginning of the Universe. Scientist have discovered that all the matter in the Universe is moving away from a central point and from all other matter at the same speed. Working backwards, they have agreed that at some point all the matter in the Universe was contained in a small, incredibly dense ball which exploded in a ‘big bang’ sending out all the matter in all directions - a bit like a huge firework rocket exploding in the sky! The time and quantities involved are beyond human comprehension, especially as it poses the question of what is outside the Universe?......
Because of the time it takes light to reach us on Earth, we are actually looking at things the way they were billions of years ago.
If someone on another planet 65 million light years away from Earth was to look at the Earth through an immensely powerful telescope today, they would see a planet with dinosaurs on it.
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Teacher's Guide
