A revolution in astronomy

A revolution in astronomy

Today, all scientists agree the Earth and planets orbit the Sun

• _{It took a long time for scientists to convince everyone...}

• We see the Sun, stars and the moon moving across the sky. It doesn't feel like we are spinning, so it was natural to think the Earth was stationary and that everything else orbited the Earth

The Geocentric System

• This picture shows this idea, which lasted to over 1500 years

• It is called the Geocentric model

Open Ended

This system is called the Geocentric model. How many other words do you know that start with 'geo'. What do these words have in common?

'Earth' is called geos in Greek

Words that start with 'geo' are all related to Earth

The problem of planets

• Astronomers have been observing stars and planets for thousands of years. There was one problem with the Geocentric model. It could not explain the unusual motion of the planets.

The problem of planets

• Over time, planets change their positions in the sky

• For example, sometimes we see Mercury and Venus at dawn, before the Sun rises

• Sometimes we see them at sunset

• This shows that they don't move at a steady speed around the Earth

Copernicus

• Astronomers came up with many complicated explanations for this

• In 1510, a Polish astronomer called Copernicus put forward a simpler explanation: ^{The Earth and other plants travel around the Sun, and other stars are very far away}

• This is called the heliocentric model because the Sun is at its centre (the Sun is helios in Greek)

Open Ended

Galileo and the telescope

• Galileo was an Italian astronomer who lived 100 years after Copernicus

• He was lucky, the telescope had just been invented and in 1609, he became the first person to use a telescope to look at the moon and the stars

Galileo and the telescope

• Galileo discovered that Jupiter had four moons orbiting it. This proved that not everything orbits the Earth

• ^{(today, we know that Jupiter has got about 80 moons!)}

Galileo and the telescope

• Many people were unhappy with the ideas Copernicus and Galileo had. They wanted to believe the Earth was the centre of the universe

• Galileo didn't have enough evidence to prove his ideas but today we know that a lot of his ideas were correct

• ^{This is a picture of Galileo}

Multiple Choice

Day and night are caused by _______________.

• Earth's rotation

• Earth's revolution

• Moon's revolution

• Moon's rotation

Multiple Choice

Which of the following do the blue arrows represent in the picture?

• A day on Earth
• Earth's rotation around the Sun
• Earth's revolution around the Sun
• A month on Earth

Multiple Choice

Which of the following amounts of time has gone by when the Moon makes 1 revolution around the Earth?

• 1 month on Earth
• 1 year on Earth
• 1 day on Earth
• 1 week on Earth

Multiple Choice

Which of the following is best shown in the picture?

• Earth's revolution
• A month on Earth
• A year on Earth
• Earth's rotation

Multiple Choice

The Catholic Church attacked Galileo because he defended they system that said the _______ revolved around the ______.

• Earth... Sun

• Sun... Earth

• Stars... Moon

• Moon... Earth

Multiple Choice

Copernicus argued that the planets revolved around the...

• Sun.

• Earth.

• Black Hole.

• Devil.

Multiple Choice

______________ improved on earlier models of the telescope to identify 4 moons of Jupiter, rings of Saturn, phases of Venus, and more to become known as the "Father of Modern Observational Astronomy."

• Copernicus
• Newton
• Galileo
• Ptolemy

Multiple Choice

Earth revolves around ________, because it has the __________ in the solar system.

• the moon; most gravitational force
• the sun; least gravitational force
• Jupiter; most gravitational
• the sun; most gravitational force

Multiple Choice

What type of orbit does the Earth have?  This was proven by astronomer Johannes Kepler.

• An elliptical orbit around the moon.
• An elliptical orbit around the Sun.
• A circular orbit around the moon.
• A circular orbit around the Sun.