1. Who realized what was going on and when…
The Great Astronomers
Who realized what was going on and when…
By Julie Shaw
Duluth Middle School

2. The Greeks These guys were amazing (and super bored)
They first noticed five points of light that wandered among the stars – they called them planets (wandering stars)

3. They named these planets
Mercury
Venus
Mars
Jupiter
And Saturn
After their gods.

4. The five planets Mercury

5. Venus

6. Mars

7. Jupiter

8. Saturn

9. Ptolemy and the Geocentric System
The Greeks thought the Earth was the center of the Universe. Ptolemy believed the moon and planets revolved around the Earth. They moved in little circles that moved in bigger circles.

10. Copernicus
Everyone believed Ptolemy for centuries, until a young upstart Polish astronomer in the early 1500s said “Hey, I think the Sun is at the center and everything is revolving around it!”
This was considered very controversial at the time, but it slowly gained support among astronomers.
This is called the heliocentric view.

11. Copernicus – Our hero

12. s
Most people still were backing Ptolemy and the geocentric view but along came Galileo and his telescope (the first telescope)
Galileo saw moons of Jupiter revolving around the mighty gas giant
He also saw Venus going through phases just like our moon.
Galileo proved Copernicus was correct.

13. Galileo – also our hero…

14. Galileo helped the Heliocentric view gain support
But the Roman Catholic Church brought him up on charges of heresy because his views countered the teachings of the Church.
Galileo was put under house arrest for the rest of his life. He died in 1642.

15. Brahe and Kepler
Up until Brahe and Kepler, two Dutch astronomers, everyone thought the orbits were perfect circles.
Brahe gathered data for years and, on his deathbed, he left his young student Kepler all of it. Kepler analyzed it and discovered that the orbits are elliptical in shape – not circles.

16. Sir Isaac Newton
This guy was absolutely brilliant. He came up with 3 Laws of motion including the Law of Gravity and the Law of Inertia.
These two laws explain why an object orbits another object in space.

17. Law of Gravity
Anything that has mass exerts a force called gravity attracting other objects to it. The tale of the apple falling on his head is believed to be true.

18. Law of Gravity

19. The Law of Inertia
An object at rest tends to remain at rest and an object in motion tends to move in a straight path unless another force acts upon it.