Just to give you an idea cawilson, your citation - source? - was about 15 times longer than the average comment on Wordie. It's usual practice here to provide a link to another site for large slabs of text. Welcome to Wordie.
Have you ever noticed that on an old £2 coins it says,
“Standing on the shoulders of giants�??
It’s part of a quote from Isaac Newton,
“If I have seen further it is by standing on the shoulders of giants.�?
Isaac Newton, Letter to Robert Hooke, February 5, 1675
(He was also insulting Hooke who was a short man and one of Newton’s rivals).
But what he was referring to was the fact that scientists can start their work following on from someone else’s earlier work. They don’t have to start again from the beginning every time. But it also means there was a time when we didn’t ‘know everything’ and we had to look and try to explain the things we saw.
Have you ever been outside at night, somewhere really dark with no street lights, and looked up at the stars? I have once in Wales in Snowdonia and it was ‘awe inspiring’, which means it was amazing and a little frightening.
Imagine a time so long ago that no one had even written any history books yet and people told stories so that important events and people from the past were remembered – battles and heroes.
Imagine you are a shepherd in that time, out on the hills all day every day looking after your sheep. Night falls, the stars come out, you look up. You don’t really understand the stars and that’s a little frightening but you know your heroic myths and legends and you start seeing patterns in the stars, playing join the dots. You see crabs and goats and bears and hunters…
They explained the stars as mythical creatures and people because that is what they knew. How you explain something depends on what you believe.
They noticed that the zodiac constellations moved across the sky – in the same patterns every year. This noticing and explaining is the start of science.
If you want to know how the stars move across the sky in a year
Then go out each night for a year and record their positions
If you want to know if they move in the same way every year
Then go out next year and look again
Once you are pretty confident of how the stars move you can try to explain why they move that way.
Now let’s jump forward in history to the time of the Ancient Greeks (this doesn’t mean they were all ancient, it means they lived in Greece a long time ago). They also wanted to understand the stars but they didn’t want to explain using myths and legends they used Logic and Laws of nature.
In science a law is something that is always true
Pythagoras was an Ancient Greek you might know his theorem about triangles?
The point is it is always true – like the total of the angles in any triangle = 180 degrees. Pythagoras and his followers were like a secret society. They thought the world was made of perfect numbers. He even drowned one of his followers for revealing that Pi = 3.14 to an outsider because it suggested that the world wasn’t mathematical, neat and perfect.
The circular star trails are blurred stars. Blurring means that something is moving. So is it us that is moving or the stars. Well, we’re sitting here. Are we moving? Is this table moving? No? So logically the stars must be moving and the Earth standing still. The Greeks used an archer for proof:
If you shoot an arrow straight up in the air and the earth is moving then you will move out from under the arrow before it falls back to earth but in practice if you shoot an arrow straight up in the air it will very likely come down again and hit you on the head. Therefore the earth is not moving and therefore the stars must be moving. So they reasoned that the earth stood still in the very centre and the stars spun around it in perfect circles. Everything always the same, perfect and unchanging, for ever…following laws of nature.
Then they noticed some ‘wandering stars’ they called planets (planet means wandering star) These wandering planets mostly followed all the other stars across the sky, east to west, but sometimes they went backwards, west to east.
The Greeks tried to find the laws that explained this behaviour – again using perfect circles – because that’s what they believed in. That’s how they explained the world and the stars. And the way they explained it looked like this spirograph The Earth stands still in the middle and the planets go mostly east to west but some times they are going backwards west to east.
This was a pretty good explanation it matched pretty well with where the planets were when you went out and looked for them in the night sky and science is all about the best explanation we have so far. We’ll use it until someone reasons out and proves a better explanation. And there is another explanation for planets appearing to sometimes go back wards:
Have you ever been in a car on the motorway and overtaken another car?
When you draw up along side the other car it can look like you’re both standing still because you’re both doing the same speed. As you move past the other car looks like its going back wards and the same thing happens with planet Earth and Planet Mars if you do this:
This was the idea of Nicolaus Copernicus he was a Polish priest, medical doctor, and astronomer [His father had died and his stern uncle looked after him and his wayward brother. Copernicus was timid and shut himself up in a tower where he did his astronomy and thought about the stars. His idea was that if the Sun was in the centre everything worked better- it was a better explanation. But he didn’t publish his ideas for year because he was afraid of being laughed at. Eventually his friends persuaded him to publish but he was on his death bed the day the book came out.
And so we’re back to where we started, “Standing on the shoulders of giants�? – Copernicus couldn’t prove that his idea about the sun being central with orbiting planets was true but scientists and astronomers that came after him did.
The telescope was invented so that better observations of the stars and planets could be made and coming right up to date in the 20th century we first sent satellites and then astronauts to gather data directly.