GALILEO GALILEI

1564-1642

The OLD View of the UNIVERSE“Ptolemaic”

The OLD View of the UNIVERSE

The moon

The OLD View of the UNIVERSE

The sun

The OLD View of the UNIVERSE

Mercury

Venus

Mars

Jupiter

Saturn

The OLD View of the UNIVERSE

The stars

Reasons for supporting the old view

Religious beliefs… Humans were God’s creation and so must be at the centre of the universe.

Some passages in the bible implied that the sun was in motion across the sky.

This may have been good enough reason for many to believe in an earth centred view but for scientists of the time their were further issues…..

Reasons for supporting the old view

Everyday we see the sun “rise”, move across the sky and “set”.

It “looks” as though the sun moves around us?

But what would the movement of the sun in the sky look like if we (the earth) were rotating on our axis and orbiting the sun?

It would look the same!!!!So this can’t be the key reason for

believing that the sun orbits the earth.

The key is our understanding of MOTION!

Learned people of the time believed that if the earth was hurtling through space we would be able to feel that motion.

Surely an object cannot keep moving unless a force is pushing/pulling it along, and we would be aware of that force????

OUR MODERN UNDERSTANDING OF MOTION SAYS….NO

A steady/straight motion requires no forces to be involved.

The argument to support the old view

If the earth was moving surely we would be able to feel the motion…

Falling objects would appear to fall sideways wouldn’t they?

MOTION OF EARTH

( you and the tree)

Surely an apple is no longer pulled along with the earth and tree as it starts to fall!...

The path you would observe….

Galileo realised that our understanding of motion was

wrong.The apple continues to move sideways with the earth and the tree as it falls….

To anyone standing on earth the apple appears to fall straight down!

The idea that things need to be pulled along to keep them moving was wrong

If you are being smart….

You may be saying…..but if we are rotating and moving round the sun we are not moving in a straight line, but a circle!

FOR US TO MOVE IN A CIRCLE WE MUST EXPERIENCE A FORCE THAT PULLS US TOWARDS THE CENTRE OF THIS CIRCLE.

WE WOULD FEEL THIS FORCE.

Can you name the force that we experience and allows us to hold our circular path…..????

All this makes the explanation more complicated, but that ‘s all.

Problems for the old view

The observations of the other planets didn’t match the model.

If you plot the path of Venus across the sky it looks a bit like this

Surely it should move in a straight line!

Other problems for the old view

Galileo had created a telescope that showed

Moons around Jupiter Craters and Mountains on the moon “Spots” on the sun

Everything should move around the earth. The planets/sun and moons were supposed to be perfect and smooth!

Birth of a new view

1530 Nicholas Copernicus came up with a “sun centred” model.

He didn’t publish it until he was on his deathbed!

The New View of the UNIVERSE“Copernican”

The New View of the UNIVERSE

The New View of the UNIVERSE

Now all the planets orbits around the sun

Stationary picture

The New View of the UNIVERSE

Stationary picture

Galileo

He spoke out in favour of the Sun centred model of the universe.

In 1633 he was put on trial by the Inquisition and found guilty of heresy.

He was sentenced to life imprisonment which was later reduced to permanent house arrest