Scale of our Solar System

We have been talking about gravity and where the largest mass is in our Solar System...this diagram gives you an idea where all the mass is!  Our big, fat, flaming, Sun!

How do we know that this scale is accurate?  If we are going to visit other planets how do we know how far away we are from a certain planet?  Who figured this out??

Eratosthenes!  He is a REALLY old dude.  He lived in Greece, near Alexandria, in 300 BC.  He heard that in Alexandria you could stick your head in a well and see a reflection of the Sun without burning your eyes out.  He knew that he had to go when the Sun was directly overhead too, and in Alexandria the Sun doesn't go directly overhead, because he knew the Earth was tilted. Instead he took a stick to Alexandria and calculated the shadow of that stick.  By doing this he could figure out what part in the circle of the Earth Alexandria was part of...

He measured the angle of the shadow, the height of the shadow, and the distance between Alexandria and Syene.  It was easy to calculate the circumference of the Earth using this information.  Eratosthenes calculated the circumference of the Earth was:  6,250 kilometers.  The real measure of the Earth today is:  6,370 kilometers!

He was only in error by 2%!! 

Another Greek astronomer, Hipparchus, was able to calculate the distance the Earth is to the Moon by observing a Solar Eclipse, using math and making some predictions. 

He drew a model of where he stood in Alexandria compared to where the Solar Eclipse was in totality.  Then he made a slim triangle did some math magic and his calculations showed the Moon was 67 Earth's from the Moon.  Our modern calculations show the Moon is 60 Earth's from the Moon!

I'm feeling a bit "stupid" right now...I don't think I would have figured anything like that out using my calculator!!

The Solar System is made up of 8 planets, some asteroids, comets, a Tesla convertible, and other smaller objects.  The ancient scientists in Greece already knew this because they stayed up in the dark and stared at the sky, every night, making observations, taking notes and drawing models of what they saw.  Think how excited they would be to use one of our telescopes?  Or the Hubble in space?  

We are going to do some observations, modeling and math ourselves as we put together the pieces of our Solar System.  

Well, I hope so!  This is Science!!