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

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)

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

The five planets Mercury

Venus

Mars

Jupiter

Saturn

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.

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.

Copernicus – Our hero

1500-1600s 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.

Galileo – also our hero…

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.

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.

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.

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.

Law of Gravity

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.